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LIGHTING CIRCUITS AND SWITCHES 


BOOKS ON PRACTICAL 
ELECTRICITY 

By Terrell Croft 

American Electricians’ Handbook 
Wiring of Finished Buildings 
Wiring for Light and Power 
Electrical Machinery 
Practical Electric Illumination 
Practical Electricity 
Central Stations 
Lighting Circuits and Switches 

POWER PLANT SERIES 

Terrell Croft 
E ditor-in-chief 

Steam Boilers 

Steam Power Plant Auxiliaries and Acces¬ 
sories 

Steam-engine Principles and Practice 
Steam-turbine Principles and Practice 
Machinery Foundations and Erection 
Practical Heat 

McGRAW-HILL BOOK COMPANY, Inc. 








' '■///rt 






































































































































































































LIGHTING CIRCUITS 


AND 


SWITCHES 


BY 


TERRELL CROFT 


CONSULTING ENGINEER. DIRECTING ENGINEER, TERRELL CROFT ENGINEERING CO. 
MEMBER OF THE AMERICAN INSTITUTE OF ELECTRICAL ENGINEERS. 
MEMBER OF THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS. 
MEMBER OF THE AMERICAN SOCIETY FOR TESTING MATERIALS. 

MEMBER OF THE ILLUMINATING ENGINEERING SOCIETY. 


First Edition 



McGRAW-HILL BOOK COMPANY, Inc. 
NEW YORK: 370^SEVENTH AVENUE 


LONDON: 6 & 8 BOUVERIE ST., E. C. 4 

1023 



TK4&55 

• 07 


Copyright, 1923, by Terrell Croft 


PRINTED IN THE UNITED STATES OP AMERICA 




,PLE PRESS - YORK PA 

JUN11 '23 

©C1A7 04049 




PREFACE 


Lighting Circuits and Switches has been prepared to 
satisfy the demand for a practical reference book on this 
subject. It shows and discusses those circuits and connec¬ 
tions, and their applications, a knowledge of which is, at 
some time or other, required by practically every man who is 
in any way concerned with electric lighting. Although the 
simpler circuits and their descriptions have been included, the 
important function of the book is to record diagrams and 
explanations of the more complicated circuits and control 
methods—with which relatively few men are familiar and 
which are, in any case, easily forgotten. 

This information has been collected from many sources. 
Most of it is from the author’s personal notebook and data 
files which have been accumulated during an extended period. 
Some has been furnished by switch and apparatus manu¬ 
facturers. Practical electrical workers, teachers, engineers in 
our own and other organizations and many others have all 
contributed. 

Throughout, the policy has been to endeavor to convey with 
pictures the necessary information to the reader. It follows 
therefore that the work consists largely of diagrams and draw¬ 
ings of the different circuits, switches and switching methods. 
These have, where feasible, been so rendered as to be self- 
evident. But, in addition, they have been supplemented 
with explanatory text. 

The material relates almost wholly to electric-lighting cir¬ 
cuits and switches, for interior building applications, operating 
on low-potential (less than 600 volts) systems. Most of the 
matter concerns 110-220 volt, two- or three-wire systems. 
Some data which relates to electric-heating circuits and 
switches has been included. The principal National Elec¬ 
trical Code rules, which concern the subjects under discus¬ 
sion, are interpreted in the proper places. How to comply 
with these Code rules is explained. 

vii 


Vlll 


PREFACE 


Certain of the circuits and diagrams have no direct practical 
application—they are shown to illustrate principles. These 
principles and the ideas which they will suggest can often be 
effectively employed in the solution of unusual circuit-control 
problems. 

In the opening divisions of the book, the different circuit 
components, such as circuit elements, switches and similar 
appliances are defined and explained. Then, those National 
EL eCTRiCAL Code rules which apply are discussed. This 
introductory material is followed by the divisions which treat 
the circuits of the different types such as Single- and Multi- 
pole Switch Circuits , Three- and Four-way Switch Circuits , 
Master or Emergency Circuits , Electrolier and Heater Switch 
Circuits and Remote-controlled , Door and Time Switch Circuits. 

The closing division discusses Theatre Lighting Circuits 
and includes a complete specification for the electric lighting 
of a modern theatre. Theatre-lighting control has, of late, 
become a subject of considerable importance and complexity. 
This is because of the exacting requirements for theatre¬ 
lighting installations which are now enforced by the producers, 
the public and the National Electrical Code. The pro¬ 
ducers and the public demand the most-comprehensive color 
and lighting effects, which involve rather-intricate and expen¬ 
sive lighting circuits and switching and dimming equipment. 
The Code insists that the fire hazard be a minimum. Both of 
these aspects have been treated carefully. 

Terrell Croft. 

University City, 

St. Louis, Missouri. 

February , 1923 . 


ACKNOWLEDGMENTS 


The author desires to acknowledge the assistance which 
has been rendered by a number of concerns and individuals 
in the preparation of this book. Some of the text material 
appeared originally as articles by the author in certain trade 
and technical periodicals, among which are: Electrical Review , 
The National Contractor, Electrical World, Electrical Engineer 
and Southern Engineer. Among the concerns which cooper¬ 
ated in supplying test data material for illustrations are: 


Bryant Electric Co. 

The Hart Mfg., Co. 

A. & J. M. Anderson Mfg. Co. 
Frank Adam Electric Co. 
Cutler-Hammer Mfg. Co. 
Mutual Electric & Machine Co. 
Trumbull Electric Mfg. Co. 
Automatic Switch Co. 

Paragon Electric Co. 

Mercury Time Switch Co. 

The Brookins Co. 


Sundh Electric Co. 

Arrow Electric Co. 

Hart & H eg email Mfg. Co. 
Beaver Machine & Tool Co. 
Connecticut Electric Co. 
General Electric Co. 

Pringle Electrical Mfg. Co. 

Syr ague Electric Works. 
Metropolitan Electric Mfg. Co. 
Electrical Mfg. Co. 

Pierce Electric Co. 


Special acknowledgment is hereby accorded to I. V. LeBow, 
Head Electrical Engineer of The Terrell Croft Engineering 
Company, who has been largely responsible for the production 
of the book and who has assisted in every possible way since 
its inception. The author is also greatly indebted to R. E. 
Major and P. Rabon, of the Major Equipment Co., Chicago, 
III., for their valuable assistance in the preparation of the 
division on Theatre Lighting Circuits. Acknowledgment is 
also hereby made to R. L. Simmers and P. A. Dates for the 
assistance, material and suggestions which they furnished. 

Other acknowledgments have been made throughout the 
book. If any has been omitted, it has been through over¬ 
sight, and if brought to the author’s attention, it will be 
incorporated in the next edition. 


IX 



CONTENTS 


Page 

Preface . vii 

Acknowledgments . ix 

Division 1.—Circuit And Switch Nomenclature. 1 

Definitions Of Circuit Components. 2 

Standard Diagram-symbols.19 

Definitions Of Various Forms Of Switches.24 

Division 2 . —Lighting Switch Construction.62 

Knife Switches.62 

Snap Switches.79 

Division 3.—Underwriters’ Requirements.117 

Knife Switch Construction.119 

Service Switches.133 

Installation Of Knife Switches.138 

Link Fuse Construction.152 

Enclosed Fuse Construction.159 

Protecting Conductors By Fuses.167 

Division 4.—Single- And Multi-pole Switch Circuits. . . . 177 

Single-pole Switch Circuits.178 

Double-pole Switch Circuits.189 

Three-pole Switch Circuits.•.208 

Division 5.—Three- And Four-way Switch Circuits.212 

Standard System.214 

Testing The Standard System.243 

Carter System. ..249 

Testing The Carter System. 256 

Division 6.—Master Or Emergency Circuits.260 

Straight Master Circuits. 265 

Universal Master Circuits. . ..277 

Rules For Connecting Master Circuits.290 

Division 7.—Electrolier And Heater Switch Circuits . . . 293 

Two-circuit Electrolier Switch Circuits.296 

Three-circuit Electrolier Switch Circuits.300 

Heater Switch Circuits.309 

Division 8.—Remote-controlled, Door And Time Switch 

Circuits.315 

Types Of Remote-controlled Switches.318 

Control Circuits.328 

Selection Of Remote Or Direct Control.339 

Applications Of Remote-controlled Switches.341 


xi 






































Xll 


CONTENTS 


Page 

Door-switch Circuits.352 

Types of Time Switches .367 

Appliances For Time Switches.370 

Applications Of Time Switches.373 

Division 9.— Theatre Lighting Circuits And Switching. . . 384 

General Requirements.384 

Services And Service Entrances.386 

Theatre Circuit Layouts.396 

Types And Circuits Of Manual And Remote Switchboards . .411 

Dimmer Connections.445 

Typical Theatre Wiring Specification.452 

Index .461 












LIGHTING CIRCUITS AND 

SWITCHES 

DIVISION I 

CIRCUIT AND SWITCH NOMENCLATURE 

1. Circuit And Switch Nomenclature Should Be Thoroughly 
Understood before proceeding with the study of circuits and 
switches. Accordingly, different circuit components and 
various classifications and types of switches which may be 
employed in an electric-light wiring interior installation are 
defined in the following sections. These definitions are in 
conformity with the generally-accepted meanings of the words. 

2. An Electric Circuit Is Defined (Fig. 1) as the complete 
path of an electric current including, usually, the generating 


■ A . C . Generator 



Fig. 1.—Illustrating various electrical circuits. (Closed circuit; CBDAC . Externa 
circuit, BDA . Internal circuit, ACB . Open circuit, O . Short circuit, S .) 

device; also, by extension, any portion of such a path. The 
complete path is often spoken of as a closed circuit. When its 
continuity is broken so that a current can no longer pass, the 
circuit is then said to be an open or broken circuit. An external 
circuit (Fig. 1) is that portion of the complete circuit external 
to the source of energy. An internal circuit (Fig. 1) is that 
portion of the circuit which is within the source of energy. 

Note.—A Short-circuit (Fig. 1) is said to exist when two sides 
(Sec. 11) of an electrical circuit which are at different potentials au 
connected, one to the other, by a conductor of relatively low resistance. 

1 















2 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 1 


3. A Feeder, or feeder circuit, (F, Figs. 2 and 3) is a set of 
conductors, in an electrical-energy distributing system, which 
extends from the original source of energy in the installation 



^-Source Of Energy In building-Wiring 



Fig. 3. Circuit-nomenclature change by changing distribution centers and 

cutouts. 


to a distributing center and which has nothing connected to it 
between the source and the center. The source of energy 





























































































































































































Sec. 4] 


DEFINITIONS AND NOMENCLATURE 


3 


may be a generating or a sub-station, or, in the case of building 
or house wiring, it may be a connection (0, Fig. 2) to the 
service conductors from the street. 

4. A Sub-feeder, (B , Figs. 2 and 3) is an extension of a 
feeder, or (Fig. 3) of another sub-feeder, connecting one dis¬ 
tribution center to another, and having no other circuit con¬ 
nected to it between the two distribution centers. 

5. A Main (ikf, Figs. 2, 3, and 4) is any supply circuit to 
which other energy-consuming circuits (sub-mains, branches, 
or services) are connected through automatic cutouts (fuses 
or circuit breakers) at different points along its length and 
which has no cutouts in series with it in its entire length. 





.■■■Generator (Source Of Energy) 





■Fuses 


A 

/Main 

V 


A - Motor M 

Branch 1 1 

Branch 

y.- Branches -.J 

1 

E 

_ lap- >fO-|T 

iEy 

6 6 da 6 




Fig. 4.—Showing a main feeding direct from a generator. (No feeder in circuit.) 


Note.—Where A Main Is Supplied By A Feeder, the main is 
frequently of a smaller-diameter wire than is the feeder which serves it. 
An energy-utilizing device is never connected directly to a main; a cut¬ 
out always being interposed between the device and the main. 

6. A Sub-main (S , Fig. 3) is a subsidiary main, fed through 
a cutout from a main, or from another sub-main, to which 
branch circuits are connected through cutouts. A sub-main 
is usually of smaller wire than is the main or other sub-main 
which serves it. 

7. A Branch, Or Branch Circuit, (E , Figs. 2, 3 and 4) is a 

set of conductors which is fed through an automatic cut¬ 
out (from a distribution center, main or sub-main) and to 
which one or more energy-consuming devices are directly con¬ 
nected, without the interposition of additional cutouts. The 
only cutout associated with a branch is that through which 
the branch is fed at the main, sub-main, or distribution 
center. 

8. A Tap, Or Tap Circuit, (T , Figs. 2 and 3) is a circuit 
serving a single energy-utilizing device which is connected 
directly to a branch without the interposition of a cutout. 





















4 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 1 


9. A Distribution Center, (x, Figs. 2 and 5) (also sometimes 
called a distributing center) in an electrical-energy-distribution 
system, is the location at which a feeder, sub-feeder, main or 
sub-main, connects to the subordinate circuits which it serves. 
The switches and automatic cutouts (fuses) for the control 
and protection of the sub-circuits are, usually, grouped at the 
distribution center. In interior-wiring parlance, a distribu¬ 
tion center is often an ar¬ 
rangement or group of fittings 
whereby two or more minor 
circuits are connected at a 
common location to another 
larger circuit. A panel box 
or a group of porcelain cut¬ 
outs is a distribution center; 
see Fig. 5. 



Fig. 6.—Illustrating definition of a 

service. 

10. A Service, Or A Service Connection, (Fig. G) is a set of 

conductors constituting an overhead or an underground con¬ 
nection between conductors in a thoroughfare (as a main 
belonging to a public service corporation) and those of an 
interior or isolated wiring system. A service serves the wiring 
system with energy. 

Note.—Circuit Nomenclature Is Governed To A Considerable 
Extent, By Distribution Centers And Cutouts. Compare Figs. 2 
and 3. By omitting, the distribution center at P, Fig. 3, the sub¬ 
feeder B of Fig. 3 is thereby changed to a main. By omitting the 
cutouts, C, Fig. 3, the main becomes a branch; and the sub-main is changed 
to a tap. 



WT77Z7 

Feeder, y ^ y Panel box * 
Sub-Feeder ,■ Q r Cabinet -' 1 
Or Ham--'' 


Fig. 5.—A distribution center. 















































































Sec. 11] 


DEFINITIONS AND NOMENCLATURE 


5 


11. A Lead, A Leg, Or A Side, Of A Circuit may be defined 
as any part of either one of the conductors between the source 
of electrical energy and any energy-consuming device. 


Example.— A Lead is illustrated in 
the earth is considered to be one 
side of the circuit. In an auto¬ 
mobile lighting and ignition sys¬ 
tem which employs a “one-wire” 
circuit, the metallic frame of the 
chassis is termed a lead. The 
meaning of the terms lead, leg, 
and side are synonomous and are 
used interchangeably. 


Fig. 7. In ground-return circuits, 



Fig. 7. —Illustrating meaning of lead, leg, 
or side of an electrical circuit. 


12. A Side Circuit, which is a term applied to a three-wire- 
neutral system, is a circuit comprising one outside or potential 
wire, the neutral conductor, and the receivers connected be¬ 
tween them. The neutral may, or may not be grounded. 
Thus, every three-wire-neutral system has two side circuits 
(AON and NPB, Fig. 8). 



Fig. 8.—Direct-current, three-wire system, (In a single-phase alternating-current, 
three-wire system, the polarities of the outside wire change from instant to instant as the 
current alternates in the direction. But at the instant shown one outside wire is nega¬ 
tive the other outside wire is positive.) 

13. A Phase-wire is any one of the conductors of a polyphase 
alternating-current circuit. 

Note.—“Phase” Is A Term Which Is Frequently Erroneously 
Applied to a phase-wire. Strictly speaking, the term phase when used 
in alternating-current terminology refers to time. 

14. A Traveler May Be Defined (Fig. 9) as: Either of the 
conductors (wires) which connect together two switches (such 
as two three-way switches, or a three-way and a four-wav 
switch, Div. 5) and which do not directly connect to an energy¬ 
consuming device, nor to a conductor on which a voltage 



























































LIGHTING CIRCUITS AND SWITCHES 


[Div. 1 


6 

normally exists. In the usual installation, only one of the 
travelers connecting any two switches carries current at an}" 
one time. 


Incandescent Lamp-. 



Fig. 9.—Illustrating meaning of traveler. 

15. Restricted Control of a lighting circuit is a control such 
that only one lamp of two or more lamps which are all on the 
same branch circuit—or only one group of lamps of two or 
more groups which are all on the same branch circuit—can be 
lighted at any one time. 



Fig. 10.—Single-line diagram—one line represents all of the wires of a circuit to illus¬ 
trate definition of “restricted control.” (Only one of the lamps, A, B, or C, can be 
lighted at any one time.) 

Explanation. —That is (Fig. 10), restricted control permits that only 
lamp A, lamp B or lamp C, can, at any one time, be lighted. 

16. Selective Control of a lighting circuit is a control such 
that all possible combinations of two or more lamps, or two or 
more groups of lamps, on the same branch circuit may be 
lighted simultaneously. 



Fig. 11. —Single-line diagram to illustrate meaning of “selective control.” (Selec¬ 
tive control is provided if, S, enables each of the following combinations to be obtained 
at any one time: All lamps off; all lamps on; A off, B and C on; B off, A and C on; C off, 
A and B on; A and B off, C on; .4 and C off, B on; B and C off, A on. These are all of 
the possible combinations for three lamps.) 

Explanation. —That is (Fig. 11) selective control is provided by the 
switch if the connections are such that each of the following combinations 
may be obtained at any one time: (1) All lamps off. (2) All lamps on. 
(3) A off, B and C on. (4) B off, A and C on. (5) C off, A and B on. 
(6) A and B off, C on. (7) A and C off, B on. (8) B and C off, A on. 



















Sec. 17] 


DEFINITIONS AND NOMENCLATURE 


7 


17. Restricted-selective Control of a lighting circuit is a 
control of two or more lamps, or groups of lamps, on the same 
branch circuit by some arrangement which enables more than 
one lamp, or group of lamps, to be lighted at one time but 
does not provide for all of the possible combinations. It is 
therefore something between restricted control (Sec. 15) and 
selective control (Sec. 16). 

Explanation. —Restricted-selective control may be said to obtain 
when the connections are such (Fig. 12) that at any one time, only: 
Lamps A and B may be lighted with C off; all lamps may be lighted; all 
lamps may be turned off. It should not be assumed that this is the only 
combination obtainable with three lamps or three groups of lamps, which 



Fig. 12. —Single-line diagram to illustrate definition of restricted-selective control. 
(Connections are such that only the following combinations are available; A and B 
lighted, C off; all lamps on; all lamps off.) 

can properly be termed restricted-selective control. Any sequence of 
any combination of two or more lamps which is not strictly restricted 
control (Sec. 15) or selective control (Sec. 16) is restricted-selective control. 
Restricted-selective control is also sometimes called electrolier control. 

18. A Switch May Be Defined as: A device which is 
primarily designed for making (closing) and breaking (opening) 
electric circuits. 

19. Symbols Of The Various Types Of Those Switches And 
Energy-consuming Devices which are most frequently used 
in the wiring diagrams contained in this book are shown in 
Figs. 13 and 14. 

20. Electric Lighting Switches May Be Classified In Accor¬ 
dance With Four Different Characteristics (see Table 21): (1) 
Blade mechanism. (2) Operating method. (3) Mounting 
design. (4) Circuit connections. Table 21 indicates how these 
various classifications interrelate in commercial electric 
lighting switches. All of the terms used in Table 21 are 
defined in subsequent sections. Also certain other switch- 
parlance terms, which are used in commercial catalogues and 
literature but which cannot logically be shown in the table, are 
also hereinafter defined. 







8 


LIGHTING 


CIRCUITS AND SWITCHES 


[Div. 1 


Genera I 


I - Conductors 
Hot Connected 


I-Conductors 
Connected 


AT TB 

Lighted Extinguished 
11'Incandescent Lamp 


H-Heater 
(Resistance) 


Point Switches 



Y-Single-Point. YI-Single-Point: 3ZE-Two-Point YE'Three-Point KrFour-Point 

Closed Open Closed Closed Open 



Rotary Snap Switches ( Surface Or Flush) 



X-Single-Pole X[-Single-Pole. XK"Double-Pole XK~Double-Pole XlY-Electrolier 
Closed Open Closed Open 



XY'Three-Way XYl-Three-Way AVll'Four-Way XY1IL-Four-Way XIX- Three-Pole 

Position 1 Position 2 Position 1 Position 2 Closed 



Upper 

Deck 


-Lower 
Deck 



-Metallic 
I Connection 
I Between 
\ Upp>erAnd 
Lower-Deck 
Blades - 



Upper-Deck 
Blade — 


i Lower- 
Deck 

v Blade --- 



Position! Position 2 Positions Position 4 

XX-Typical Multi-Deck Switch. (Electrolier And Series -Parallel) 


Push-Button SnapSwitches (SurfaceOrFlush.Oscillating Blade) 

% 


a 

£ 



Ml 

a a 

M 



Xxl- Single-Fble XXll'Singe-Pole XXlll-Double-Pole XXW -Douhle-Pole XXY-Three-Way 


Closed 


Open 





Open 


4 


K 



XXVI-Three-Way. XX.V1L-Four-Way X XVIII Four-Way 

Position 2 Position! Position 2 


XXIX-Momentary Contact. 
Open Closed 


Fig. 13.—Wiring-diagram symbols. 



















































































































































































Sec. 21] 


DEFINITIONS AND NOMENCLATURE 


9 


Knife Switches 


7k - 77 

77- - 7 


T — 

-TP 


rk -fi 

14= — 

1 a 11 


^- 

r=- 

d~ 


a a 

a a 

Closed 

Open 




T ^ T 


_ t __ Open 

XXX. - Single-Pole, Single-Throw XXXI - Double-Pole, Single-Throw 


1 


‘ 5 - 


=E 


a 

§ 

i" 

§ 

_ 



Closed 


Open 


H 1=3“ 3=1_ 


Position 1 


Position 2 


XXXK-Three-Pole, Single-Throw XXXIII-Single-Pole, Double-Throw 


Tii f~ I 7 


Closed Open 



Closed Open 

XXXY-Three-Pole, Double-Throv 


XXXT?-Two-Pole, Double-Throw 

Fig. 14.—Wiring diagram symbols. (Continued from Fig. 13.) 


21. Table Showing Classification Of Electric Lighting 
Switches. (Tabulating switches of different types as they are 
manufactured.) 


Blade mechanism 

Operating 

methods 

Mounting design 

Circuit connections 

Revolving blade 

Rotary-button 

Surface, flush. 

1-, 2-, and 3-pole; 3- 
and 4-way; electro¬ 
lier; and series-para- 
[llel. 

Push-button. 

Surface, flush, pen¬ 
dent, straight- 
through. 

1-, and 2-pole; 3- and 
4-way; electrolier; 

series-parallel ; and 
momentary contact. 

Pull. 

Surface, flush, pen¬ 
dent. 

Same as above. 

Oscillating blade 

Toggle-lever or 
tumbler. 

Surface, flush, pen¬ 
dent. 

Same as above. 

Push-button. 

. 

Surface, flush, pen¬ 
dent. 

Straight-through. 

1-pole. 

Knife blade. 

Knife-handle. 

Surface. 1-, 2-, 3-, and 4-pole, 

single- and double¬ 
throw. 

Lever blade. 

Rotary-button, 

knife-handle. 

Surface. 

1-, 2-, 3-, and 4-point, 
etc. 

Reciprocating blade.. 

Push-button. 

Surface, pendent. 

1-pole. 





























































































































10 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 1 


22. Electric Lighting Switches May Be Further Classified 
As To Blade Mechanism into: (1) Revolving-blade switches. 
(2) Oscillating-blade switches. (3) Knife-blade switches. (4) 
Lever-blade switches. (5) Reciprocating-blade switches. 

23. A Revolving-blade-mechanism Switch Is Defined, 


(Fig. 15) as the term is used in 



Fig. 15.—Illustrating operation of re¬ 
volving- (rotating-) blade switch. 


this book, as a switch the con- 



Fig. 16.—Rotary surface “snap” switch. 


tact blade or blades of which are pivoted at their centers and 
when operated turn always in the same direction. The 
ordinary surface “snap” switch (Fig. 16) affords an illustration 
of this type of blade mechanism. 



.-Contact 

m 




Contact-., 

Conductor -->1 

Fig. 17. —Illustrating definition of os¬ 
cillating-blade switch mechanism. 


Blade Swings In Plane 

At Right Angles To Base-. nC-c-/ 

y 

/ 

/ 

/#, 

/'oV 


Y" ''$> 


Pivot At End 
Of Blade--. 


.-Blade 


Insulating 

Handle-- 


"iV 


m be 


Closed 


1 


a 




Y -Mounting Base (Insulation) 

Conductor 


Fig. 18.—Illustrating definition of knife- 
blade mechanism switch. 


24. An Oscillating-blade-mechanism Switch Is Defined 

(Fig. 17) as one, the blade or blades of which are pivoted on a 
central axis located midway between the blade ends and 
which are oscillated in a plane at right angles to the axis when 






















































Sec. 25J 


DEFINITIONS AND NOMENCLATURE 


11 


the switch is operated. Many flush push-button switches 
employ blade mechanisms of this type. 

25. A Knife-blade-mechanism Switch Is Defined (Fig. 18) 
as one the contact blade (blades) of which is (are) pivoted 
at one end on an axis (common axis) and swings (swing) in 
a plane (planes) perpendicular to the mounting base of the 
switch. The blade of a knife-blade mechanism switch is 
hinged at one end like the blade of a jack-knife. The ordinary 
knife switch (Fig. 18) illustrates this mechanism. 

26. A Lever-blade-mechanism Switch May Be Defined 
as one the blade of which is so pivoted at one end that, when 






Fig. i 9 —Single-point, two-point, three-point and four-point switches. 

the switch is operated by the handle at the other end, this 
handle-end swings in a circle in a plane parallel to the base 
and contacts with buttons or jaws located on the circumference 
of the circle. See Fig. 19. The one-, two-, three- and four- 
point switches employ blade mechanisms of this type. 

































12 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 1 


27. A Reciprocating-blade Mechanism Switch (Fig. 20) is 
one the blade of which is shifted to and fro longitudinally in 
a straight line when the switch is operated. 

Explanation.— In The Reciprocating-blade Switch Mechanism, 
Fig. 20, the cylindrical “knob,” K, is integral with the metal button, M, 
so that when M is pushed in or pulled out, K moves with it. The spring, 
S, is an ordinary coil spring which has its two ends tied together, so that 
it is in the shape of a ring. This ring-shaped spiral spring encircles, and 
its inner circumference always presses against the cylindrical surface of A. 
At I, the spring, S, being under tension, tends to contract—decrease its 
diameter—and thereby forces K to the right and holds the blade, B, 
in the position shown. The blade B is not attached to K. 



Binding 

Posts 


Contact Composition 
Points . Insulating Block 


Mounting- Screw 
Hole 


Front 
Plate - 




* Metal 
Push 
Button. 

Ring-/ 

Shaped 
Spiral 

Spring j-Open Position 


Assembling Screw 


'Knob K 


H-Closed Position 


I-Middle Position 


Fig. 20.—Reciprocating-blade-mechanism switch for automobile lighting. (Cutler 

Hammer Mfg. Co.) 


At II, M has been pulled outward to the middle position. The 
barrell-shaped knob, K, having been pulled through the spring, S, 
increased the diameter of S, thus producing an additional tension in the 
spring. 

As soon as M is drawn a little further outward (to the left) than is 
shown at II, then the point of maximum diameter of K will be on the 
left-hand side of the spring. Since the spring is under tension it will tend 
to decrease its diameter. This forces S to slide along K to the right— 
toward a point of smaller diameter. The spring in sliding along K, 
strikes the cross-piece C, which is fastened to the blade, B, and it thereby 
carries B to the right and causes B to contact with the jaws, J, as shown 
at III. Thus, the switch is closed. In opening the switch, the operation 
is substantially the reverse of that just described. 

28. Electric Lighting Switches May Be Further Classified 
As To Operating Method into (Table 21): (1) Rotary-button 

switches. (2) Push-button switches. (3) Pull-switches. (4) 
Toggle-lever or tumbler switches. (5) Knife-handle switches. 









































































Sec. 29] 


DEFINITIONS AND NOMENCLATURE 


13 


29. A Rotary-button Switch (Fig. 16) is defined as one the 
operation of which is effected by turning a button. 

30. A Push-button Switch (Fig. 21) is defined as one the 
operation of which is effected by pushing a 
button. Some switches of this type have 
only one button while others have two (see 
Div. 2.) 


Note.—Push-button Switches Are Manu¬ 
factured In Both The Surface And Flush 
Types; and, as shown in Table 21, may have either 
revolving-blade or oscillating-blade mechanisms. 
However, rotary-button switches are usually made 
(with revolving-blade mechanism) in the surface type, 
and push-button switches in the flush type. 





31. A Pull-switch is one (Fig. 22) the opera¬ 

tion of which is effected by pulling a chain Fig< 21.—Flush 
or cord. Usually one pull on the chain closes switch of the push- 
the switch and the next pull opens it. button type- 

32. A Toggle-lever Or 
Tumbler Switch (Fig. 23) is 
one which is operated by 
moving a small lever which 
extends from the switch. 


Switch 

Plate 


Porcelain' 


Fig. 22.—Ceiling-type pull-switch. 


Fig. 2'S. — Flush toggle or tumbler 
switch and switch plate, with switch box 
removed. 


33. A Knife-handle Switch (Fig. 18) is one which is 
operated directly by a handle which is attached, without 


















































14 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 1 


intervening mechanism, to the swinging end of the switch 
blade or blades. This operating method is principally 
employed for knife-blade switches. 

34. Electric Lighting Switches May Be Further Classified 
As To Mounting Design into: (1) Surface switches . (2) Flush 

switches. (3) Pendent switches. (4) Straight- 
through switches (see Table 21). 

35. A Surface Switch (Figs. 16 and 22) 
is one which is designed primarily for 
mounting on an exposed surface and which 
is so made that none of it extends inward 
through the surface. See Table 21 for 
variations in the application and design. 

36. A Flush Switch (Fig. 21) is one which 
is designed primarily for installation in, and 
so that its outer face will be practically 
flush with, the surface of a wall or 
partition (see Secs. 101 and 146). 

Note.—The Terms “Surface” And “Flush” 
As Used In Switch Nomenclature are usually 
applied to switches of the “snap” type. 

37. A Pendent Switch (Fig. 24) is one which is designed for 
installation on the end of a flexible cord which usually hangs 
suspended from some point above. 



Fig. 25. —A straight-through switch. (Beaver Machine & Tool Co., Newark, N. J .) 


38. A Straight-through Switch (Fig. 25) is one which is 
designed for mounting in a flexible conductor so that the 
conductor enters and leaves the switch in a practically-straight 



Fig. 2 4.—Pendent 
switch. 


























































Sec. 39] 


DEFINITIONS AND NOMENCLATURE 


15 


line. It is sometimes called a feed-through switch, or a cord, 
switch. 

N 

Note.—The Underwriters’ Laboratories Define A Pendent 
Switch as: “A switch designed to be installed at the end of or in the 
middle of a flexible cord.” Such a definition will include switches of 
each of the types as defined in Secs. 37 and 38. 

39. A Snap Switch is, strictly speaking, any switch which 
opens and closes with a “snap,” regardless of how rapidly or 
slowly its operating button or handle is moved by the person 
who operates it. An automatic spring-actuated mechanism 
within the switch provides this action. All electric-lighting 
switches should, to conform to the National Electrical Code 
recommendation (Rule 246) be quick-break or snap switches. 
However, certain switch manufacturers use the term “snap 
switch” to designate only a rotary-button-operated surface 
switches as for example that of Fig. 16. 

40 . Electric Lighting Switches May Be Further Classified As 
To Circuit Connections (see Table 21) into: (1) One-point 
switches. (2) Two-point switches. (3) Three-point switches. 

(4 ) Four-point switches. (5) N-point switches, the letter “iV” 
being used as a symbol to indicate any number of “points.” 

(5) Single-pole or one-pole switches. (6) Double-pole or two-pole 
switches. (7) Triple-pole or three-pole switches. (8) Four-pole 
switches. (9) N-pole switches, the letter “N” being used as a 
symbol to indicate any number of poles. (10) Three-way 
switches. (11) Four-way switches. (12) Single-throw switches. 
(13) Double-throw switches. (14) Electrolier switches. (15) 
Series-parallel or heater switches. All of the types which have 
just been listed are defined and illustrated in subsequent 
sections. There may also be other circuit-connections and 
sub-classifications. 

41 . A “Switch-position,” Or The “Position” Of A Switch 
May Be Defined As any stationary position of a switch-blade 
which will provide a certain definite circuit-connection within 
the switch. That is, a two-position switch is a switch wherein 
the blade or blades have two, or more, stationary positions 
which provide only two different circuit-connections. A three- 
position switch provides only three different circuit connec- 


16 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 1 


tions. A single-throw knife-switch has two positions, 
“open” and “closed.” A double-throw knife-switch may be 
connected to provide either two or three positions, “closed 
right,” “open” and “closed left.” Snap-switches which have 
more than four positions are seldom manufactured (see 
Secs. 86, 93, 296, and 299). 

42. Much Confusion Has Resulted From Erroneous Switch 
Terminology As Regards The Terms “Three-point,” “Three- 
pole,” and “Three-way.” Any or all of these terms are 
frequently used in describing the same switch (see Figs. 
13 and 14). Also, four-point, four-pole, and four-way are 
often used interchangeably in designating the same device. 
Some switch-manufacturers have called their three-way and 
four-way switches, three-point and four-point switches. This 
has increased the confusion. Each of these terms has a 
certain definite meaning, and should only be applied to a 
certain definite type of switch. Specific definitions of this 
switch terminology are given in the following sections. 

43. The Definition Of A One-point, Or Single-point, 
Switch (Fig. 19-7) may be stated as: A switch which has a 
metallic lever so pivoted at one end, that when the lever , is 
rotated about the pivot as a center, the other end which moves 
in a circular arc will make contact with a stationary metallic 
button, called a contact button. One conductor (A, Fig. 19-7) 
is connected to the pivoted-end of the lever, and another con¬ 
ductor, B, is connected to the contact button. Switches of 
this type are usually employed only in low-voltage signal work. 

44. The Definition Of A Two-point, A Three-point, Or A 
Four-point Switch (Fig. 19-77, -777, -IV) may be given as: A 
switch which is identical with the one-point switch in opera¬ 
tion, and in construction (Sec. 43), except that there are, 
respectively, two, three, and four contact buttons on a two-, a 
three-, and a four-point switch. Thus, with a four-point 
switch, an electric circuit (Fig. 26) may be closed through the 
battery, P, and any one of the four subsidiary circuits, A, B, 
C, or D, by placing the switch lever on the contact button, 
a, b, c, or d, and then closing the push-button, M. 

Note.— A Push-button Should Be Installed In Any Multi¬ 
circuit Signalling System Which Employs A Three- Or A Four- 


Sec. 45] 


DEFINITIONS AND NOMENCLATURE 


17 


point Switch. The necessity for this is that should the metallic lever be 
rotated from contact button a to d (Fig. 26) the lever might, in being 
shifted, make contact with buttons b and c, thereby causing lamps B and 
C to light, momentarily, before the lever could reach d. 

45. A Single-pole Or One-pole Switch May Be Defined 

as: A switch whereby only one conductor, or lead, of an elec¬ 
tric circuit can be opened or closed (see Figs. 19-7,27-7 and 30). 



Fig. 26. —Showing signalling instal¬ 
lation controlled by a four-point®switch 
and push-button. 


■ Handle 


Jaw- 



Blade■■■ 
Post- 


A 


: qp- 
Hr' # 




I-Single-Pole Switch 1-Two-Pole Switch 



UrThree-Pole Switch Ur Four-Pole Switch 


Fig. 27. —Single-pole, two-pole, three- 
pole and four-pole single-throw knife 
switches. 


46. A Double-pole Or Two-pole Switch May Be Defined 

(Fig. 27-77) as: A switch whereby two conductors, or leads, 
of an electrical circuit, or two conductors, or leads, of two 
separate circuits, may simultaneously be opened or closed. 

47. A Three-pole Switch May Be Defined as: A switch 
whereby each of three leads of a circuit, or of different circuits, 
can be simultaneously connected or disconnected (see Fig. 
1S-XIX and Fig. 27-777). 

48. A Four-pole Switch May Be Defined as: One whereby 
each of four legs of a circuit, or of different circuits, can be 
simultaneously connected or disconnected (see Fig. 27-7 V). 

Note.—An N-pole Switch May Be Defined as: A switch whereby 
each of N (any number) leads of a circuit, or of different circuits, can 
simultaneously be connected or disconnected. From a consideration 
of Fig. 27, it will be noted that if four single-pole knife switches be 
mounted parallel to each other on a flat insulating base and the four 
handles connected together by a strip of rigid insulating material, a four- 
pole switch (Fig. 27-IV) will result. Switches having more than four- 
poles are seldom used. 

2 






















































































18 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


49. The Definition Of A Three-way Switch may be stated 
as: A switch (Fig. 28) which has four binding posts, two 
adjacent posts (A and B) being permanently connected by a 
shunt, S, so located that the contact bar, C, will, when moved 
around a central pivot, effect an electric connection between 
diagonally-opposite binding posts (see Div. 5). A three-way 
switch is sometimes called a combination switch. It should not 
be called a three-point switch or a three-pole switch. 




Fig. 28.—Diagram of a three-way switch. Fig. 29.—Diagram of a four-way switch. 

50. A Four-way Switch May Be Defined as: A switch (Fig. 
29) which has four binding posts and two contact bars, which 
are insulated from each other, so arranged that by moving 
the contact bars around a central pivot, electrical connection 
can be effected between any two adjacent posts and simultane¬ 
ously connection is made between the other two posts. This 
type of switch is sometimes called a commutating switch. 
It is also incorrectly called a four-point switch or four-pole 
switch. 

Note.—This Definition Of A Four-way Switch Is Based On The 
Construction Of These Switches As They Are Usually Manufac¬ 
tured. A double-pole double-throw switch (Sec. 229) may, however, be 
so wired that the connections which it effects are equivalent to those made 
by a four-way switch. 

51. A Single-throw Switch May Be Defined as: A switch 
(Figs. 27 and 30) the blades or contact bars of which, when 
operated, contact with only one set of contacts. As indicated 
in Fig. 27, single throw switches may be of either the single¬ 
pole or multi-pole type but they need not necessarily have 





















Sec. 52] 


DEFINITIONS AND NOMENCLATURE 


19 


knife-blade mechanisms, though the use of the term is usually 
confined to mechanisms of this type. 


. -Leads. . >\Jcrw-. 


''Blade 


Porcelain V 
Base 

n\\ r- 



1-Single-Pole 

Double-Throw 




I-Double-Pole, 
Double-Throw 


..r ; 

r 'Contact 
Bar. A* 

''Binding-Post-' 

Fig. 30.—Principle of operation of single¬ 
pole, single-throw snap switch. 



Leads- 


Blade - 


H-Three-Pole, 

Double-Throw 



E - Four-Pole, 
Double-Throw 


Fig. 31.—Illustrating various types of 
double-throw knife switches. 



z—• 

L-' 

Electrolier 


Switch' 


[ 




y.-NP/Vot 


\ J 



'Voltage Supply 


B 


Lamp 




Position 1; AH Off 



52. A Double-throw Switch May Be Defined as: A switch 
(usually a knife switch), Fig. 31, wherein the blades, or contact 
bars, may be operated to make 
contact with either of two sets 
of binding posts, or contacts. 

As shown by Fig. 31, double¬ 
throw switches may be of either 
the single- or multipole type. 

Double-pole, double-throw 
switches are also manufactured 
in the snap type. 

53. An Electrolier Switch May 
Be Defined as: A switch which 
has its binding posts and contact 
bars so arranged that two or more 
energy - utilizing - device circuits 
may be controlled by placing the 
contact bars in different po¬ 
sitions. A diagram of a simple 
electrolier switch-circuit is shown 

in Fig. 32 (see also Div. 7). 

54. A Series-parallel Or Fig - 32—Illustrative diagram of an 

_ ^ „ electrolier switch and its circuits. 

Heater Switch May Be Defined 

as: A switch which has its binding posts and contact bars so 
arranged and connected that two or more energy-consuming- 






































































































20 LIGHTING CIRCUITS AND SWITCHES [Div. 1 

device circuits may, by successive operations of the contact 
bars, be connected into the circuit either in parallel or in 
series. Such an arrangement, employing a double-throw, 
double-pole knife switch is shown in Fig. 33. This switch is 
also furnished by manufacturers in the snap type (see Div. 7). 




Source Of E. M. F. 


Vx 


Ji 


Switch Box 


V/////////////7777L 

v 




Pivot- 


'f-. 

K* 


Tjk 

<■Contact 
Bar 

-Spring 



Contact 

fa Lrtir 


V 


XA//////////// ///r///A 

Binding Posts--' 


Fig. 33.—Double-throw, double-pole Fig. 34.—Diagram of a two-circuit mo- 
knife switch having two binding-posts mentary-contact switch, 

connected by shunt, S, to form a series- 
parallel switch. 


55. A Momentary-contact Switch May Be Defined (Fig. 34) 
as: A switch which operates to close one or more circuits only 
while force is exerted on its contact bar. Switches of this 
class are usually made in the push-button type (see Divs. 2 
and 8). 

56. A Master Switch is any switch which is so connected 
that it may be operated to light or to extinguish simultane¬ 
ously all of the lamps, or only specially designated ones, in an 
installation, irrespective of the positions or operation of the 
switches which regularly control the individual lamps or 
circuits (see Div. 6). This definition applies specifically to 
lighting circuits of all buildings except theatres. See note 
below. 

Note.—The Term “Master Switch” As Used In Theatre Par¬ 
lance has a meaning which is somewhat different from that defined 
above (see Sec. 416). 

57. A Service Switch (0, Fig. 2) is a switch through which 
the service wires (Fig. 6) connect to a building-interior wiring 










































































Sec. 58] DEFINITIONS AND NOMENCLATURE 21 

system. It is (except as outlined in Sec. 134) so connected 
that it will, when open, disconnect from the source of supply 
all devices and wiring which are within the building. 

58. A Barrier is defined as a non-combustible, non-absorp- 
tive insulating block which is placed between current-carrying 
parts of opposite polarity to prevent arcing or “flash-overs” 
between the parts. 

Examples. —Barriers (Sec. 129) are often placed on knife switches 
between the hinge jaws, the break jaws and the metallic supporting 
blocks. They may be of sheet asbestos, of slate, or of similar materials. 
Barriers, usually of concrete, are arranged between busbars in station 
switching structures. Barriers of porcelain, cast integral with the base, 
are frequently provided on porcelain fusible-cutout-and-switch bases. 

59. A Sub-base (Fig. 159) is defined as a non-combustible, 
non-absorptive insulating block which is installed under flush 
snap switches or other electrical devices which are designed for 
surface mounting—and which is so constructed as to raise the 
switch or device off of the surface and to prevent the con¬ 
ductors which enter the switch or device from contacting with 
the supporting surface. 

Note.—Sub-bases Are Usually Made Of Porcelain (see. Div. 3) 
but wooden sub-bases may be used under certain conditions. Also 
sub-bases are sometimes made of marble, slate, glass or other materials 
which will satisfy the requirements which are specified above. 

60. A Cutout, as the term is applied in electrical parlance, 
is defined as device which is so constructed that it will 
automatically open any circuit, in which it is connected in 
series, when the current in that circuit exceeds the value at 
which the cutout is designed or adjusted to operate. Sec 
Fig. 168 for an illustration of a fuse cutout. 

Examples. —An automatic overload circuit breaker, or a fuse mounted 
in a cutout base are examples of cutouts. The Code considers that a 
cutout base and a fuse which the base carries constitute a cutout. 
Commercially, the base and receptacle which are designed to carry the 
fuse are called a cutout. 

Explanation. —When the current through a fuse exceeds, for a 
relatively-short time, the ampere current rating value which is printed 
or stamped on the fuse, then the fuse wire will melt and thereby open 
the circuit in which it is connected in series. When the current through 
an overload circuit-breaker exceeds the ampere current value for which the 


22 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 1 


breaker is set, then the breaker will trip and open the circuit in which it is 
connected in series. Thus an overload circuit-breaker opens instan¬ 
taneously when the current through it exceeds the value for which it is 
set. A time-limit circuit-breaker will not open until after the current for 
which it is set has flowed through it for a certain predetermined time for 
which the breaker is also set. 

61. A Panel Board (Fig. 5) is a device upon which are 
mounted fuse receptacles and switches—or cutouts and 
switches, S, —for the control and protection of the branch 
circuits, B, which are fed from the main, M, supplying the 
energy to that panel board. A panel board usually has two 
or more branch circuits leading from it. These branch cir¬ 
cuits are fed from busbars, E, which are connected to the 
main, M. This device is ordinarily enclosed in a protective 
box, which is called a panel-box or cabinet. The complete 
apparatus—the cabinet and the panel, board—is sometimes 
termed a distribution center (Sec. 9). 

QUESTIONS ON DIVISION 1 

1. Define the following terms: Electric circuit; closed circuit; open circuit; external 
circuit; internal circuit; short circuit. 

2. Draw a sketch to illustrate each of the terms which you have defined in Question 1. 

3. Define a feeder. 

4. In circuit nomenclature, what may be considered as the source of energy? 

5. What is a sub-feeder? Main? Sub-main? Branch? Tap? 

6. Draw a sketch illustrating each of the terms mentioned in Question 5. 

7. What is a distribution center? 

8. What is a service? Make a sketch to illustrate. 

9. Define a lead. What other terms may be used interchangeably with lead? Give 
examples. 

10. What is a phase-wire? What term is frequently erroneously used for phase-ivire? 

11. What is a traveler? Draw a sketch to illustrate. 

12. What two devices largely govern circuit terminology? 

13. Show by sketches: How a sub-feeder may be changed to a main; how a main may 
be changed to a branch; how a branch may be changed to a tap. 

14. What terms are frequently incorrectly applied to the same switches? 

15. Define a switch. 

16. What is a one-point switch? Two-point switch? Three-point sivitch? Four- 
point switch. Draw a sketch of each. 

17. For what applications are point-switches generally used? 

18. What other type of switch should be employed in connection with a three- or a 
four-point switch? Why? 

19. Define a single-pole switch; double-pole switch; three-pole switch. 

20. Make a sketch of and define a three-way switch; four-way switch. 

21. What other type of switch may be used to provide four-way-switch control? 

22. What is a double-throw switch? 

23. Define: Electrolier switch; series-parallel switch; momentary-contact switch. 

24. Draw a diagrammatic sketch showing the operation of each of the switches men¬ 
tioned in Questions 22 and 23. 

25. What is a master switch? 


DIVISION 2 


LIGHTING-SWITCH CONSTRUCTION 


62. Knife Switches, Or Lever Switches, Are Simple In 
Construction. A thorough and complete understanding of the 
operation of, and of the available circuits through a knife 
switch may be readily obtained by a cursory examination of it. 
The purpose of the following sections relating to knife switches, 
is to present various features of construction that are at 
present embodied in knife switches by the principal 
manufacturers. 

63. The Names Of Knife-switch Parts are given in Fig. 35. 
Every knife switch has one or more metallic blades, B, each 
blade being so hinged at one end to a metallic post, P,—hinge- 


Insulating 
Base I - 


Insulating 
Cross-Bar C - 



Contact- 
Block- . [ 


B 

O 

Blade^ 



.■Contact 
: Block 



3==?ilC 

Blades* ; P<;: ’ Lugs \ 

"" "iM 


b5G3 - Insulating/ 


^ Handle--' £ 


I-S ingle - Blade D-Two-Bla ol e 

Fig. 35.—Illustrating nomenclature of knife-switch parts. 


jaw—that by operating B, which moves in a plane perpendicular 
to the base, about P as a pivot, the opposite end of each of the 
blades will fit into and make contact with a metallic jaw, J — 
break-jaw. This opposite end of the blades is equipped with 
a handle, II, which is made of insulating material. In those 
switches of the multi-blade (multi-polar) type, a cross-bar, C, 
which is made of an insulating material, rigidly connects the 
blades together. The hinge-jaws, P, and the break-jaws, J, 
are usually equipped with some sort of binding-post or lug, L. 
The binding-posts, which are mounted on an insulating 

23 







































































24 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


base, I f are merely for convenience in connecting and discon¬ 
necting the current-carrying wires. 

64. The Materials Used In Knife-switch Construction May 
Be Classified as: (1) Conductors or current-carrying parts. 
All current-carrying parts of knife switches are ordinarily 
made of copper. (2) Insulators or non-current-carrying parts. 
The binding-posts, blades, jaws and contact-blocks (Fig. 35) 
comprise the current-carrying parts. The base, handle, and 
cross-bar (Fig. 35) comprise the non-current-carrying parts. 
Various forms in which each of these parts are made and the 
methods of fastening one part to another are described in the 
following sections. 

65. Knife-switch Blades ( B , Fig. 35) are usually stamped or 
machined from solid hard-drawn copper of about 98 per cent, 
conductivity (see note below), and then, in the best construc¬ 
tion, ground flat. The maximum current-carrying capacity 
allowed for the blades of knife switches is about 1,000 amp. per 
sq. in. of cross-sectional area. That is, if a switch is to carry a 
current of 600 amp., the cross-sectional area of the blade must 
be at least: 600 A- 1,000 = 0.6 sq. in. However, in the 
small-capacity knife switches, this minimum-allowable cross- 
sectional area (0.001 sq. in. per amp.) of the blades is, to secure 
sufficient stiffness and mechanical strength, usually exceeded 
—frequently being as large as 0.025 sq. in. per rated ampere or 
400 amp. per sq. in. Even in the large-capacity switches, 
manufacturers usually, to take care of accidental overload, 
make the cross-sectional blade-area somewhat greater than 
the minimum allowed. 

Note.—The Maximum Temperature Rise Of The Switch Parts 
Over The Temperature Of The Surrounding Air Should Really 
Determine The Minimum Amount Of Material Which Should Be 
Incorporated In Any Given Switch. The “maximum temperature 
rise” is that attained while the switch is carrying continuously its rated 
full-load current. Rules such as those given above serve as guides, but a 
temperature-rise test should be the final criterion. In its Standard 
For Snap Switches the Underwriters' Laboratories specifies that, “all 
snap switches, must have ample metal for stiffness and to prevent rise in 
temperature of any part over 54° F. (30° C.) at full load. The 
American Institute Of Electrical Engineers Standardization 
Rules specifies this same maximum temperature rise for all switches. 


Sec. 66] 


UGH TING-S WITCH CONSTR UCTION 


25 


Note.—Solid Hard-drawn Copper Has A Conductivity Of 98 Per 
Cent, if 1 g. of the material, when drawn into a wire of uniform 
circular-cross-section and 1 m. in length, has a resistance of 0.15,538 
ohms at a temperature of 20° C. (68° F.). 

66. Knife-switch Jaws are made of copper. For the suc¬ 
cessful operation of a knife switch, it is essential that the jaws 
make firm contact with the blades. This is accomplished by 
making the jaws of resilient “springy” hard drawn copper. 
Several different forms of jaws (Fig. 36) are used. The 
principal forms are described below. The break-jaws of 



H* Break Jaw 


End View Side View 

IV-Hinge Jaw 


Y'Hinge Jaw 


Fig. 36.—^Showing various forms of knife-switch jaws. 


Fig. 36 -I are made by sweating and pinning the jaws, J, to 
the contact-block, C. Those shown at II and III are made of 
hard sheet copper, which is pressed into the forms shown. The 
break-jaws are frequently provided with a screw, rivet, or 
bolt (S, Fig. 36-/ and II) to form a stop to prevent the switch 
blade from being pushed too far down into the jaws; it may 
also be used to adjust the distance D. The two different types 
of hinge-jaws, IV and V, are constructed in a manner similar 
to that of the break-jaws of I and II, respectively. 

67. Knife-switch-blade Hinges (Fig. 37) usually consist of 
a bolt inserted in the hinge-jaws, thus forming a pivot about 
which the blades may rotate. In switches of cheaper grades, 

















































26 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


this pivot is sometimes merely a rivet with its heads spun over. 
A construction which provides a ready means of adjusting 
the hinge-jaw is shown in Fig. 37. The stud, S, is threaded on 
both ends. Each end is then provided with two nuts—a 


Blade B 


Holding Nut---.^ 
Lock Nut--;-s> r 

N t 

" ~5tud 1 

Spring Washer - 

H / 









Its 







J 

w 



Contact - Bloc K 








I-Side View H-End View 


Fig. 37. —Blade hinge for knife-switch hinge-jaw. 


holding-nut, H, and a lock-nut, N —and a spring-washer, W. 
This spring washer is preferably made of spring brass or 
phospor bronze but it may be of steel where the switch will not 
be exposed to moisture. When the assembly is made as shown 


Fig. 38. — Knife switch provided with extended hinge-jaws so that the switch blades 

may be locked in the open position. 



in the illustration, the nuts may be tightened down on the 
spring-washers, thus insuring firm contact between the blade, 
B, and the jaws, J. 

Note.—The Switch Blades May Be Locked In The Open Position 
by using a pad-lock in connection with a hinge-jaw of the type shown 
















































£ec. 68] 


LIGHTING-SWITCH CONSTRUCTION 


27 


in Fig. 38. Such a device is desirable where a workman may wish to 
lock “dead’’ a certain part of the line upon which he may be working. 

Note.—Stops Which Limit The Arc Of Switch-blade Throw 
To 90 Deg. may be provided on the hinge-jaws as shown in Fig. 39. 
This permits the'mounting of switches and other apparatus in a smaller 
space than that which would be required if it were necessary to provide 
sufficient clearance to throw the blades all the way 
over through an angle of 180 deg. 

68. Knife-switch Jaws Must Be So Secured 
To The Base That They Cannot Turn On 
The Base. This is done by means of dowel- 
pins or screws as described in Sec. 126, or 
in some instances, where jaws of the type 
shown in Fig.'36-7/, III and V are used, a 
square hole is countersunk into the base 
(Fig. 40), and the jaw, which is fitted into 
the square hole, is secured to the base by a 
single screw. 

69. The Wires Are Connected To Knife Switches By Means 
Of Binding-posts (Fig. 40). The point of connection is also 
sometimes called the switch terminal. In front-connected 
knife switches (Fig. 41)—wherein the wires are connected to the 
switch on the same side of the base as that upon which the 



Fig. 39. — Stop- 
mechanism to limit 
the arc of switch- 
throw. 


Square Holes To Prevenf 



Fig. 40. —Showing the method of pre¬ 
venting switch jaws from being turned on 
the base by fitting them into counter¬ 
sunk square holes. 



Fig. 41.—Showing connecting-lugs on a 
front-connected switch. 


switch is mounted—the binding-posts frequently consist 
of one of the contact-block holding-bolts. However, in 
Fig. 40, the terminal which carries the binding-post is separate 
from the jaw, and is secured thereto by the jaw holding-screw. 



































































28 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


In back-connected knife switches (Fig. 42)—wherein the wires 
are connected to the switch on the side of the base opposite to 
that upon which the switch is mounted—the binding-posts 
take the form of a stud, S. One end of this stud is soldered 
into the contact-block. The wire, if of a size No. 8 gage, or 
smaller, is secured to the other end of the stud by nuts. 



Fig. 42. —Showing connecting-lugs on a back-connected switch. (Switches of this type 

are permitted only on switchboards.) 


Note.—Connecting-lugs Must Be Used In Connecting Wires Of 
A Size Larger Than No. 8, B. & S. Gage, To Switches (Code Rule 
16 c.) The lug is secured to the binding-post (Fig. 41), or to the stud 
(Fig. 42) by a nut or nuts, and the wire is soldered into the lug. Various 
types of connecting-lugs or terminals are shown in Fig. 43. 




n-Terminal Lugs For Back - Connected Switches 
Fig. 43.—Showing various types of knife-switch connecting-lugs. 

70. The Materials Of Which Knife-switch Bases Are 
Constructed are, because of Underwriters’ (Sec. 121) and 
service requirements, practically limited to the following: (1) 
Marble. . (2) Slate. (3) Porcelain. (4) Composition such as 
hard fiber, bakelite, transite or “moulded mica.” The 
large-capacity switches are generally provided with slate or 



































































Sec. 71J 


LIGHTING-SWITCH CONSTR UCTION 


29 


Combined Handle 


marble bases, while the bases for those of small capacity are 
usually of porcelain or a patented composition. Slate is, for 
voltage under 1,000, preferable because it is the stronger. 

71. The Blades Of Multi-pole Knife Switches Are Mechani¬ 
cally Connected Together By A Bar Of Insulating Material 
Called A Cross-bar (C, Fig. 35 -II). This cross-bar is usually 
made of hardwood, composition, or fibre, which is machined 
to shape and, often, polished. In some of the small-capacity 
switches, the cross-bar is made of porcelain. The cross-bar is 
in the better switches secured to the blade by means of a blade- 
block, (B, Fig. 41) which is fitted into a groove in the cross¬ 
bar and held therein with screws, bolts 
or rivets. In some low-priced switches, 
the end of the blade is bent over, and 
screwed to the cross-bar as shown in 
Fig. 40. 

72. Knife-switch Handles (H , Fig. 

35) are usually made of hard-wood. 

They are shaped in a turning-lathe 
and then heavily enameled or varnished. 

However, some switch handles are made- 
of porcelain or composition. The handle 
is, in single-pole switches (Fig. 35-7), secured to the blade by 
a blade-block and a screw or bolt. The blade-block is soldered, 
sweated, or pinned to the blade. The screw or bolt, which 
passes through the handle longitudinally, is then screwed into 



Fig. 44.— Fibre spade- 
handle often used on 30- 
amp., double-pole switches. 



1-Wide Type II-Angle Type H-Narrow Type 

Fig. 45.—Types of spade-handles used on large-capacity multi-pole switches. 

the blade-block. In multi-pole switches (Fig. 35-77), the 
handle is fastened to the cross-bar by a bolt. In the small 
30-amp. switches which are used on distributing panels the 
composition handles (Fig. 44) form both a cross-bar and a 
handle. Spade-handles (Fig. 45) are often used on large- 
capacity switches because of the more convenient and effective 























30 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


grip which they afford. “Spool” handles (Fig. 46) are also 
frequently used for 30-amp. switches. 



Fig. 46.—A 30-amp. panel-board switch having a spool-handle. 

73. Knife Switches May Be Classified According To The 
Form Of The Switch as shown in Table 74. That is, knife- 
switches are made single-, double-, three-, four-, five-, and 
six-pole; single- or double-throw; fused or unfused. If any 
of the above combinations are unfused, they may be provided 
with either front or back connections (Sec. 69). If they are 
fused, the fuse terminals may be located on either the front 
or on the back of the base, and may be of such a type as to 
hold either link or cartridge fuses. If front-fused, the switch 
may be either front- or back-connected. However, if the 
switch is back-fused, it is usually back-connected. 

74. Table Showing Knife-switch Classification According 
To The Form Of The Switch. 


Pole 

Throw Fuses 

1 

Connected 

Single. 

Double. 

Three. 

Four. 

Five. 

Six. 

Single. 

Double. 

No fuse 

Front. 

Back. 

Front-fused. 

Open link. 
Cartridge. 

Front. 

Back. 

Back-fused. 

Open link. 
Cartridge. 

Back. 













































Sec. 75] 


LIGHTING-SWITCH CONSTR UCTION 


31 


75. Knife-switch Troubles usually first reveal themselves 
by the switch becoming heated. These troubles are ordinarily 
caused by: (1) Loose terminals. (2) Improper contact between 
the blade and jaws. The remedy for the first-mentioned trouble 
is, obviously, to tighten the loose connection. A method of 
locating and correcting the second trouble is described in the 
following section. 

Note.—The Maximum-allowable Current Density At The 
Blade-and-jaw Contact Of A Knife Switch is about 75 amp. per sq. 
in. That is, the total contact-area between the blade and the jaw of a 
100-amp. switch should at least be: 100 -f- 75 = 1.33 sq. in., or: 1.33 -f- 
2 =0.67 sq. in. on each side of the blade. If the jaws become deformed 
so that only two edges of the jaws contact with the blade, a large over¬ 
load of the small contact area will result and the switch will thereby 
become heated. 

76. A Test For Proper Blade-and-jaw Contact may be made 
by trying to insert a piece of very thin mica or paper between 
the jaw and the blade at the corners and sides. The thickness 
of this “feeler” should not exceed one or two mils (0.001 to 
0.002 in.). If the “feeler” can be inserted between the blade 
and jaw at any point, it is evident that the contact is bad. 
Another means of locating an improper blade-and-jaw contact, 
which may sometimes be used, is: Hold the switch between 
the eye and a strong light. Move the switch about so that 
the contact may be examined from every possible angle. If 
light can be seen between the blade and jaw, the contact is 
bad. If improper contact is found to exist, it may be corrected 
by the method which is outlined in the following section. 

77. A Poor Blade-and-jaw-contact May Be Corrected by 
the following procedure: If the bad contact is at the hinge- 
jaw, it may usually be remedied by tightening the nut or the 
rivet of the hinge-pivot. If it .is at the break-jaw, the jaws 
may first be bent into a more-nearly correct position either 
by hand or by driving a block of wood against the jaw with a 
hammer. Then apply a mixture of vaseline and fine pumice 
stone (FF) to the contact-surfaces of the blade and jaw, and 
work the blade in and out several times. The bending of the 
jaws increases the friction between the blade and jaws, and 
the working-in-and-out process grinds off any “high places.” 


32 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


This grinding not only improves the “fit/ 7 but removes any 
lacquer or other foreign material, which is sometimes the 
cause of bad contact. The switch should, of course, be entirely 
isolated from any source of voltage during the above operations. 

78. Table Showing Approximate Selling Prices Of 250-volt 
Front-connected Knife Switches Mounted On Slate Base And 
Provided With Cartridge Fuse Terminals. (The cost of the 
switches will vary somewhat, depending upon the locality 
and the quantity purchased. The prices of similar switches, 
which are back-connected, which have open link fuse ter¬ 
minals or no fuse terminals will not vary greatly from the 
prices shown. Switches for 500 volts cost relatively little 
more than 250-volt switches.) 


Current rat¬ 
ing, Amp. 

Form 

Single-pole 

Double-pole 

. 

Three-pole 

Single¬ 

throw 

Double¬ 

throw 

Single¬ 

throw 

Double¬ 

throw 

Single¬ 

throw' 

Double¬ 

throw 

30 

$ 2.15 

$ 3.25 

$ 3.75 

$5.75 

$ 5.25 

$ 8.30 

60 

2.65 

3.85 

4.60 

7.10 

6.65 

10.65 

100 

4.60 

7.35 

8.55 

14.00 

12.55 

20.85 

200 

6.50 

10.85 

12.70 

20.90 

18.75 

31.00 

400 

10.75 

17.35 

21.10 

35.00 

31.30 

51.75 

600 

16.95 

27.20 

33.05 

54.. 70 

49.10 

81.25 

800 

23.10 

36.85 

44.50 

71.15 

66.20 

107.10 

1,000 

29.50 

48.90 

58.15 

94.15 

86.55 

141.80 

1,200 

33.40 

54.45 

65.85 

105.10 

98.10 

158.00 


79. The Mechanisms Of Snap Switches May Be Considered 
As Consisting Of Three Elements : (1) Conductors, or current- 
carrying parts. (2) Insulators, or non-current-carrying parts. 
(3) Operating mechanism. While the operating mechanism is 
always made of conductor-material (metal), it does not 
normally carry current. Each of these elements is described 
in the following sections. Various snap-switch elements are 
shown in Figs. 47, 48, 49, and 50. 





























Sec. 80] 


LIGHTINGS WITCH CON ST R UCTIO N 


33 


* 80. The Conductors, Or Current-carrying Parts, Of Snap 

Switches (Sec. 39) are the: (1) Binding-posts, (P, Figs. 51 and 
52). (2) Stationary contractors, ( C , Figs. 51 and 52). (3) 

Movable contactor, or blade, (B, Fig. 52). Various forms, and 



Fig. 47.—Showing arrangement of 
binding-posts, and method of fastening 
notched plate to porcelain base, for a 
single-pole, surface snap switch. 



Fig. 48.—Section of porcelain base show 
ing eccentric on shaft. 


the materials of manufacture, which are employed in the 
construction of snap-switch current-carrying parts are 
discussed in the following sections. 



Fig. 49. — Movable-contactor 
and indicating dial for single¬ 
pole, revolving-blade snap switch. 



Porcelain 

Base-^ 

Movable 

Contactor 


Stationary 

Contactor 


Fig. 50. —Single-pole, revolving-blade, sur¬ 
face snap switch with cover removed. 


81. The Binding-posts —also called terminal plates —( P, 
Figs. 51 and 52) are the devices which hold the wires to the 
switch. The binding-posts (P, Fig. 51) are in electrical 
contact with the stationary contactor, C. Thus, when the 
movable contactor (P, Fig. 52) makes contact with the sta¬ 
tionary contactors, C, a current-path through the switch is 

3 







































34 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


established. The binding-posts are usually made of brass. 
They are made in innumerable different forms and shapes. 



Fig. 51. Fig. 52. 

Fig. 51.—Showing one type of snap-switch binding-post with wire attached. (Hart 
Mfg. Co.) In wiring this binding-post, it is unnecessary to remove the binding screw 
or to loop the wire. The wire, after being skinned, is simply inserted in the post and 
then bent forward around the screw. It is then cut off to proper length. With a screw 
driver, the loose end is pressed under the head of the screw and the screw tightened. 

Fig. 52.—Nomenclature of snap-switch current-carrying parts. (Movable contactor 
consists of a flat plate, and stationary contactors are of the jaw type.) 


Fig. 



I-Skinned Wire-End 
Inserted 


53.—Method of “making 


H-Wire-End Bent 
Over And Held 
By Lip 


H-Screw Tightened 
Down And Wire-End 
Clipped Off 


up” connection in surface switch binding-post. (Arrow 
Electric Co.) 


For examples of various forms of binding-posts, see Figs. 
52, 53, 55 and 63. 



































































Sec. 82] 


LIGHTING-SWITCH CONSTRUCTION 


35 


82. The Principal Types Of Contactor-mechanisms are: 
(.1) The movable-plate-and-stalionary-j aw ^contactor, (Fig. 52), 



Fig. 54. —Illustrating contactor mech¬ 
anism wherein the movable contactor, B, 
is of the jaw type and the stationary con¬ 
tactor, C, is of the plate type. 



Fig. 55. —Illustrating end-contact type 
of contactors. 



Holding 
Screw ■ 


Movable 

Contactor 


Stationary 
Contactor • 


'Stationary 

Contactor 


Shaft 


V: Binding > 
- . Post- . ’ 

.Screw To Hold Wire 
To Binding Post. :A 


Fig. 56.—Single-pole, rotating-button snap switch having end-contactor mechanism. 

(Switch open, button and cover removed.) 


wherein the movable contactor, B consists ot a flat plate, the 
ends of which fit between the jaws of the stationary contactors, 
































LIGHTING CIRCUITS AND SWITCHES 


IDiv. 2 


36 


C. (2) The movable-jaw-and-stationary-plaie contactor , (Fig. 
54), wherein the movable contactor. B, consists of jaws, 



Fig. 57. —Single-pole, rotating-button, snap switch having end-contactor mechanism. 

(Switch closed, button and cover removed.) 



Fig. 58. —Illustrating different shapes of rotating-blade snap-switch movable contactors. 

between which the flat-plate stationary contactors, C, fit. 
(3) The end-contactor, (Figs. 55, 56, and 57), wherein the ends 
of the movable contactor, ( B , Fig. 55), rub against the station- 























Sec. 83] 


LIGHTING-SWITCH CONSTRUCTION 


3 i 


ary contactor, C. Those parts of a contactor-mechanism 
which must “spring” or “give” (C, Figs. 52 and 55; B, Fig. 54) 
are, usually, made of phosphor-bronze. Those parts which 
are not required to be resilient ( B , Figs. 52 and 55; C, Fig. 54) 
are, usually, made of brass. Revolving-blade movable 
contactors of various shapes are shown in Fig. 58. 

83. Snap Switches Are So Made, With Non-current Carry¬ 
ing Parts Of Insulating Material That There Are No Exposed 
Live Parts which might incur a life or fire hazard. These non¬ 
current-carrying parts consist of: (1) A porcelain or molded- 
composition base (Figs. 63 and 96-7), upon which the 


Movable 

Contactor. 


-■-Shaft 

Fig. 59.—Method of insulating the 
movable contactor from the operating 
mechanism. (Hart Mfg. Co.) 

binding-posts and the operating mechanism are mounted. 
(2) The insulating material which prevents the movable con¬ 
tactor from making electrical connection with the operating 
mechanism (Figs. 59 and 77). This latter insulating material 
usually consists of sheet mica or fibre. 

Note.—Not All Of The Non-current Carrying Parts Of A Snap 
Switch Are Made Of Insulating Material. Although the operating 
mechanism, and frequently the switch cover, are of conductor-material, 
normally they do not carry current, since they are, as explained above, 
insulated from the current-carrying parts. 

Note.—A Snap-switch Base Also Supports The Switch Operating 
Mechanism (Figs. 62 and 65). For surface and flush switches, (Figs. 63 
and 67) the base is usually made of porcelain. Other forms of switches, 
such as the feed-through switch of Fig. 96 and the canopy switch of 
Fig. 100 have bases made of a patented insulating composition. The 



Insulating-Fiber Lining - Notch 



Fig. 60.—Metal cover lined with insu¬ 
lating material. (Notch N , fits on a lug 
carried by the base to prevent cover 
from turning.) 































































38 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


switch mechanism for flush switches is completely enclosed on five sides, 
(Fig. 69) by a porcelain casing or container. 


84. Metal Covers On Rotating-button Snap Switches Are 
Lined With A Fibre Insulating-material as shown in Fig. 60. 
Such an insulating lining is intended to prevent accidental 
short-circuiting of the binding-posts while removing or putting 
on the switch cover. 


Note.—The Button, Or Handle Of A Snap switch (Figs. 16 and 
68) is also of an insulating material: Usually molded-composition or 
porcelain. Normally the shaft, ( S , Fig. 61) is not in contact with a 
source of voltage, but the button is made of insulating material merely 
as an additional precaution against the exposure of live parts to accidental 
contact. 



I-Switch Handle 
For k Rotating- 

button Snap- 
Switch 



Button-..^ 
'Springfe 


E-5pring In 
Normal Position 



5hafB _ _ 

Itt-5pring Compressed When button 
Is 5crewed On Tightly 


Fig. 61.—Showing one method of holding cover snugly to the base. (Hart Mfg. Co.) 


Note.—Various Devices Are Employed To Hold The Cover Of A 
Surface Snap Switch Snugly Against The Base, one of which is 
illustrated in Fig. 61 -II and III , and another in Fig. 62. When the 
button ( B , Fig. 61 -III) is screwed on to the shaft, S, the spring, C, is 
compressed. The tension of C, acting downward against the button, 
holds the cover, D, tightly against the base. The spring washer, W, of 
Fig. 62 performs the same function. 

85. An Almost Infinite Number Of Different Operating 
Mechanisms Are Employed In Snap-switch Construction. 

Only a few, of the various types of operating mechanisms for 
the different forms of switches, are described herein in the 
following sections. The complicated construction of the snap- 
switch mechanisms is necessary to insure the “snap” action 
which is explained in the following note. 

Note.—The Basic Principle Underlying The Operation Of 
Practically All Snap Switches is as follows: During the operation of a 
handle, the tension in a spring is increased. When the operation of 

















































Sec. 86] LIGHTING-SWITCH CONSTRUCTION 39 

the handle has proceeded to a certain predetermined point, the blade, 
or movable contactor, is released. Upon the release of the movable 
contactor, the tension in the spring acts to move the movable contactor 
quickly through a predetermined distance. Hence, this movement 
of the movable contactor opens or closes the switch with an almost 
instantaneous “snap” action. The above operation will be more readily 
understood by a consideration of the 
following sections, wherein the func¬ 
tioning of various snap-switch mech¬ 
anisms are described. 

86. The Rotating-button, 

Revolving-blade Snap Switches, 

which are shown in Figs. 62 and 
63 are single-pole, two-position, 
single-deck (Sec. 107) switches. 

By the term two-position is 
meant that the movable con¬ 
tactor, B has two stationary 
positions each of which provides 
a different internal circuit- 
connection (see Sec. 41). These 
two positions are at right-angles 
to each other. When, in one of 
the positions, as shown in the 
illustration, B and B are in 
contact with the stationary con¬ 
tactors, C and C. Then the 
switch is said to be in the on- 
position, on, or closed. When 
the switch is operated and the 
movable contactor turns to the 
other position, B and B is not 
in contact with C and C, and 
the switch is then said to be in 
the off-position, off, or open. The operation of this switch 

mechanism may be understood from a consideration of the 

%/ 

following explanation. 

Explanation. —The button-handle (II, Fig. 63) is rigidly fastened to 
the shaft, S, so that when II is rotated, S rotates with it. The movable 
contactor, B, and the plate, D , are rigidly fastened together. The shaft 




Fig. 62. —Illustrating construction 
of single-pole, surface, snap switch of 
the rotating-button type. ( Connecti¬ 
cut Electric Mfg. Co.) 























































40 


LIGHTING CIRCUITS AND SWITCHES 


]Div. 2 


S fits loosely in D so that S may be rotated without causing B and D to 
rotate. A flat circular “eccentric” metal-punching, ( R , Fig. 64; shown 
also at R, Fig. 63) is rigidly fastened to S, so as to form a cam. This 
cam, R, is of the same thickness as the catch, T , and works in the oval- 
shaped hole in T as shown in Fig. 64 -I. The catch, T, is provided 
with a raised lug, L, which fits into a hole in D (Fig. 63). The plate, D, is 
not shown in Fig. 64. The notched metal plate ( N , Figs. 63 and 64) 
is held stationary by lugs which fit into slots in the porcelain base, P. 

The spring ( E , Fig. 63) has its upper end fastened to the shaft, and its 
lower end fastened to D. The tension in E tends to rotate S in the left- 
hand direction. However, S cannot rotate to the left because R bears 



Fig. 63.—Rotating-button snap switch. (Arrow Electric Co., List No. 6207.) 


against the side of the oval-shaped hole (Fig. 64-/) in T, and T is held 
stationary by L fitting into the hole in D. Since the tension in the spring 
tends to rotate the shaft to the left, it will tend to cause D —also B —to 
rotate to the right. Also, since D engages with T by means of the lug, 
L, T will have a tendency toward right-hand rotation. Right-hand 
rotation of T is normally prevented by the lip, K, which engages with the 
notch in N (Fig. 64-7). 

The switch is operated by turning the button, II, to the right, or clock¬ 
wise. This, as explained above, rotates the shaft, and likewise the cam, 
R. Rotation of the cam, R, causes T (Fig. 64) to swing about L as a 
center, until it reaches the position as shown in Fig. 64-/7, at which posi¬ 
tion the lip, K, is disengaged from the notch in N. When this disengage- 






























































































































Sec. 87] 


LIGHTING-SWITCH CONSTRUCTION 


41 


ment occurs, T is free to move. Since T is free to move, D is also free to 
move. Thus, when T is released, the spring-tension, acting on D and 
consequently on B, “snaps’’ the movable contactor, B, to the right until 
K engages with the next notch in N, as shown at Fig. 64 -III. Thus, the 
movable contactor has been rotated through an angle of 90 deg., or 
Irom one of its positions to the other. Since one operation of the switch 
causes both the movable contactor and the shaft to rotate in the same 
direction and through the same angle, they are, after operation, in the 
same relative position as before the operation. Thus, the spring-tension 
remains practically the same throughout any number of successive 
operations. 



Fig. 64. —Illustrating operation of rotating-button snap switch. {List No. 6207, Arroiv 

Electric Co.) 


87. Another Type Of Rotating-button, Revolving-blade 
Snap-switch Mechanism is shown in Fig. 65. The spring, S, 
is fastened to the shaft, F, at A, and to the plate, D, at 
E. This plate, D, carries the movable contactor, B. The 
operation of this mechanism is illustrated in Fig. 66. To 
understand the operation, which is explained below, refer to 
both Figs. 65 and 66. The same reference letters are used on 
both illustrations, but on neither are all reference letters 
shown. 

Explanation. —The spring, (S, Fig. 65) which is “wound up,” tends to 
rotate the lock-plate ( D , Figs. 65 and 66) to the right as shown by 
the arrow in Fig. 66-1; and tends to rotate the shaft, F, to the left. 
But D cannot rotate to the right because the slot (G, Fig. 66-/) engages 
a projecting lug, H, on the catch, J. Furthermore, J cannot rotate 
because the hook K, bears against the stationary lug, L. The holding- 
plate, M, which carries the lug, L, is held stationary by the porcelain base. 
A flat circular metal piece, ( N Fig. 66-7), is keyed to F, so that N is off 
























42 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


center, thus forming an eccentric. The shaft cannot rotate to the left 
because of a notch in N which engages a projection in .7 as shown in 
Fig. 66-7. 



Shaft- 


Bmohng Post- 


Stationary 
Contactor- „ 


Movable _ 
Contactor 


S. uq.v/g/y 

'Holding Plate 


flock-Plate-. 


W/M 


Button ■ 


Fig. 65.—Showing mechanism of rotating-button, snap switch. (Bryant Electric Co.) 



Plate Tends To Rotate Switch Blade 



I-First Position 


I* Movable Contactor J[- Second Position 

About To Be Released 


1' ig. 66. Illustrating the operation of the mechanism of a rotating-button, snap 

switch. (Bryant Electric Co.) 


In operating the switch, the button is turned to the right. This, 
through the eccentric, N, moves J downward, as shown in Fig. 66-77, 
until K is released from the lug, L. This leaves J and D free to rotate! 


























































































Sec. 88] 


UGH TING-SWITCH CONST R UCTION 


43 


Since, as explained above, the spring tends to cause a right-hand rotation 
of D, D now turns to the right with a “snap,” carrying the movable 
contactor, B, with it, until K, strikes the next lug, L, Fig. 66 -III. The 
movable contactors have thus been rotated through an angle of 90 deg., 
or from one position to a second position. 

88. Push-button Snap Switches May Be Classified as: 

(1) A one-button snap switch. (2) A two-button snap switch. 
Practically all one-button snap switches (Fig. 67) are of the 
revolving-blade type (Sec. 23). Whereas, the majority of the 
two-button snap switches are of the oscillating-blade type 
(Sec. 24). A push-button snap switch is sometimes called a 
push switch. Switches of each of the above-mentioned types 
are described in the following sections. 

89. A One-button, Snap Switch Of The Push-button Flush 
Type, Which Has A Revolving-blade Mechanism, is shown in 
Fig. 67. The snap-action mechanism is identical with that 
described under Sec. 87 in connection with Figs. 65 and 66. 
However, the rotation of the shaft in Fig. 67, instead of being 
produced by turning a button, as in Figs. 65 and 66, is pro¬ 
duced as follows: 

Explanation. —The push-button, A, Fig. 67, contains an internally- 
threaded sleeve which fits over the external threads on the shaft, S. The 
collar, D, is rigidly secured to the button. In each end of D is a slot 
which fits loosely over the posts, E. The posts, E are riveted into the 
sub-plate, F. Thus, the button, A cannot turn. Therefore, when A is 
pressed downward, S rotates. Rotation of S operates a dog- and- 
ratchet mechanism, contained in R. This dog-and-ratchet mechanism 
operates to rotate the main shaft of the switch. This rotation releases 
the snap-action mechanism. The rotation of the movable contactors 
then occurs as described in Sec. 87. The hollow button, A, contains a 
coil-spring which is compressed when the button is pushed inward. 
Then, when the outside pressure on the button is released, the spring 
expands and carries the button outward to the original position. Every¬ 
thing is then in readiness for a second operation. 

90. Two One-button Snap Switches May Be Contained In 
A Single Porcelain Casing as shown in Fig. 68. The operation 
of each switch is the same as that described in Sec. 89. Each 
switch can be operated by its own button independently of the 
other switch. Practically any two forms of switches which 
are desired, such as two single-pole switches, one three-way 


44 


LIGHTING CIRCUITS AND SWITCHES 


' [Div. 2 


Threads On Shaft 

l /Shaft ySub-Plate 

/ 

pgjjUpe 

I/, 


i»i7 /- • 



Wz&zf&s- Ratchet 
'WM: Mechanism 


Stationary 

Contactor 


Bindinq 

Post 


' Movable 


r. 'Contactor 


A 


Porcelain 

Cover 




Porcelain 

Cover 


Push-Button- 

Stationary 
Contactor 


■Movable Contactor 


-Shunt 


''Sub-Plate 


JLL - I O p VI 

Ratchet Mechanism 


e w 

/Movable Contactor 


-Bindinq 

Post 


Bindinq 
Post - 


Stationary 
Contactor ~ 


M-Top View. Button knot Sub-Plate Removed 


Fig. G7.—Push-button snap switch. (One-button, revolving-blade, mechanism. List 

No. 2458, Bryant Electric Co.) 






























































































































Sec. 91] 


LIGIITING-SWITCH CONS TR UCTION 


45 


switch and one single-pole switch, one single-pole switch and 
one electrolier switch, and so on, may be used. The arrange¬ 
ment shown in Fig. 68 consists of two single-pole switches 
which have a common feed. That is, two of the stationary 
contactors are connected to the same binding-post. 



TL- S i d e View 


Fig. 68.—Two one-button, push snap-switches mounted in a single porcelain cover. 
(The illustration represents two single-pole switches having a common feed. List 
No. 2639, Bryant Electric Co.) 

91. A “Release-catch” Two-button, Single-pole, Flush 
Snap Switch is shown in Fig. 69. As hereinbefore stated 
(Sec. 88), nearly all two-button snap switches are of the oscil- 
lating-blade type. That is, by pressing one of the buttons, 
the blade is caused to rotate with a quick snap action, through 
some arc of a circle—usually about 85 or 90 deg. Then by 
pressing the other button, the blade movement is reversed— 








































































































4(i 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


that is, it rotates through the same arc in the opposite direction. 
Thus, by pressing first one button and then the other, the 
blade, or blades, oscillate back and forth. As shown at III , 



ig. 69, the switch is closed, or in the on-position. By pressing 
on the right-hand button, the rocker, R, rotates around the 
pivot T. This causes the movable contactor, B, to rotate, 












































































































Sec. 92] 


LIGHTING-SWITCH CONSTR UCTION 


47 


in the direction shown by the arrow, through an angle of 
approximately 90 deg., about the shaft, S, as a center. Thus, 
after rotation 5 and C do not contact, and the switch is open. 
Then, by pressing the left-hand button, the action is reversed, 
and the switch is thereby closed. The operation is explained 
in detail below. 

Explanation. —The operation of the two-button, flush snap switch 
of Fig. 69 is illustrated in Fig. 70. The switch-parts in Fig. 70 bear the 
same reference letters as corresponding parts in Fig. 69. In Fig. 70-7, 
the switch is in the off-position, and is held there by the spring, E, as 
follows: One end of E presses to the left against the cross-piece, G, which 



I* First Position I-Position Just Before The 

Movement Of The Blades Occurs. 


Fig. 70.—Illustrating operation of a two-button, flush, snap-switch mechanism of the 

release-catch type. (Bryant Electric Co.) 

is carried by the rocker, R. The other end of E presses to the right 
against the cross-piece, II, which is carried by the movable contactor, B. 
The cross-piece, 77, is prevented from moving to the right by the prong- 
on the ratchet, J. 

To operate the switch, button A is pushed downward. This action, by 
rotating the rocker, R, about the pivot T, carries G to the right as shown 
in Fig. 70-77. This movement of G to the right spreads the ends of the 
spring, thus increasing the tension therein. Also, as R is rotated about 
T, the ratchet, J, is caused to move upward, so that when R has almost 
reached its extreme position the prong of the ratchet slips out of 77 as 
shown at 77. This leaves 77 free to move. Thus, 77 being free to move, 
the spring-tension rotates, with a vigorous snap-action, the movable 
contactor, B, around the shaft, S, as a center, until 77 strikes the frame as 
shown in Fig. 69-777. The switch is now in the on-position or closed. 
When the pressure on A is released—after the movable contactor, B. is 
in the position shown at 777—the ratchet-spring, L, moves 










































48 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


in the position shown at III —the ratchet-spring, L, moves the ratchet 
downward so that the right-hand prong of the ratchet engages and 
holds H in the same manner as shown at Fig. 70-7. If button D is 
now pushed, the operation explained above is reversed, and the movable 
contactor will be rotated, in the opposite direction, to the open position. 

92. A Lever-type, Two-button, Flush Snap-switch Mech¬ 
anism is illustrated in Fig. 71. See also Fig. 83 and 
accompanying explanation. As shown at III, the movable 
contactor, B, and the stationary contactors, C, are in contact. 
Hence, the switch is closed. By pushing the left-hand push¬ 
button, the movable contactor, B, is caused to rotate with a 
quick snap-action movement through an angle of about 80 
or 90 deg. Then, since B and C are no longer in contact the 
switch is open. A detailed explanation of the operation of 
this type of switch mechanism is given below. 

Explanation. —The discussion which follows refers chiefly to Fig. 72. 
However, those reference letters which appear in both Figs. 71 and 72 are 
applied to corresponding parts. As shown in Fig 72-7, the spring, S, 
acting on the rocker-cross-piece, F, and the movable-contactor-cross¬ 
piece, G, tends to push F upward and to the left, and it tends to push G 
downward and to the right. Therefore, this spring-pressure holds the 
movable contactor, B, in the position as shown at 7. Assume that the 
stationary contactors (C, Fig. 71, not shown in Fig. 72) are so located that 
when B is in the position as shown in Fig. 72-7, the switch is closed, and 
is therefore, held by the spring in the closed position, as explained above. 

By pressing downward on button A, the rocker, R, rotates about the 
pivot, E. This causes F to move downward and to the right, thus 
compressing the spring, as shown in 77. As soon as R has rotated beyond 
the position of 77, the spring tension acts to force F upward and to the 
right, and to force G downward and to the left. However, when R has 
reached the position shown in 77, it is almost to the end of its travel. 
Therefore, the spring acting downward and to the left on G, moves G to 
the left with a “snap,” until it reaches the position shown in 777. This 
movement of G rotates the movable contactor, B, about a circular 
shoulder, K , which is carried by the stationary frame, H, to the position 
shown in 777, thus opening the switch. To reclose the switch, the above- 
described operation is merely reversed. 

93. A Two-button, Snap Switch, Which Has The Buttons 
Arranged In Tandem is shown in Figs. 73 and 74. This 
switch mechanism operates on the oscillating-blade principle 
(Sec. 91). Pushing one of the buttons causes the blade to 
rotate through about 90 deg. Pushing the other button 


Sec. 93] LIGHTING-SWITCH CONSTRUCTION 49 

causes the same blade-rotation in the opposite direction. 
Thus, the switch is opened and closed. Each of these rota¬ 
tions occurs with a snap action as explained below. 



Explanation. —The mechanism shown in Figs. 73 and 74 is ( Cutler- 
Hammer Mfg. Co.) known as the “ Hill-And-Valley” movement. The 
reference used in Figs. 73 and 74 refer to the same parts as those in 
4 


Fig. 71.—Lever-type, two-button, flush snap switch. (A part of the porcelain is broken out to show the mechanism. 

Bryant Electric Co.) 







































































































50 


LIGHTING CIRCUITS AND SWITCHES 


[Drv. 2 



Movable Con factor 

I-On Position 


Movable Contactor Cross-Piece 

F-Position Just Before 

Switch-Blade Movement Occurs 


II-Off Position 


Fig. 72.—Illustrating operation of a two button, flush snap-switch mechanism of the 

lever-type. ( Bryant Electric Co.) 



bind in a 
Post 

Terminal 

••Plate 


-Hill 


Push \ 
button 


Stationary 
Contactor 

.-Wires 

I-Top View Cover Removed 



1-Section X-Y 


Fig. 73.—Tandem, two-button, straight-through snap switch. (List No. 7050, Cutler- 

Hammer Mfg. Co.) 








































































































































































Sec. 93] 


LIGHTING-SWITCH CONSTRUCTION 


51 


Fig. 75. The movable contactor (B, Fig. 75) carries two lugs, 
L, one of which normally rests in the middle or lowest point of the valley, 
V (Fig. 75-7), and the other rests at the foot of the hill, H. This holds 
the blade in the open position shown at 7. 


Fig. 




Base--' 


-Cover Base 

Insulating 
Lining 

Stationary 
Contactor- 

Support ing- 
5crew Hole — 

Movable 
Contactor- 


BincHna. 
'Post 


■Push- 

Button 


Push- 
Button-r 


I-Sec-t ion X-Y 


H-Top View; Cover Removed 


74 .—Single-pole, tandem, two-button, surface snap switch. (List No. 7108, 

Cutler-Hammer Mfg. Co.) 


If the right-hand button is pushed to the left, the vallev-lug slides up 
the side of the valley and the hill-lug slides up the side of the hill, as 



'A-Spring 

; • Movable Contactor 


Push- 
L Button 


1 Stationary 


Contactor 


Top View 

H' Position Just Before 
Blade-Movement Occurs 


Top View 

H-Closed Position 


Top View 
I*0pen Position 

. * *: 

Movable J 
Contactor 


£ Shaft 


'Stationary Contactors 


Side View 

C, 



Fv 

/ o / 



r0/ 

* s JS 

y 

TT~7o 


k 





—. 

L—^ 

r .1 



U-Showing Construction Of Movable And 
Stationary Contactors 


p IG 75 .—Illustrating the operation of the hill-and-valley snap-switch mechanism. 


shown at 77. This tends to rotate the upper end of B to the left (Top 
View, 77), and also to rotate the lower end of B to the left. Conse¬ 
quently, no rotation can yet occur. However, the two lugs, L, one sliding 























































































































































































52 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


up the valley and one up the hill, do raise the movable contactor upward, 
thus compressing the spring, S, as shown in II. A consideration of IV 
will disclose how B may be raised and yet B and C still remain in contact 
with each other. When the button is pushed a little farther to the left 
than is shown at II, the hill-lug will slip over the top of the hill. The 
compressed spring ( S, Fig. 75 -II), pushing downward on B, then causes 
the hill-lug to slide down the hill and the valley-lug to slide back down the 
valley. This causes a quick snap-action rotation of B in a left-hand 
direction, thus closing the switch. If now the left-hand button is pushed 
to the right, the switch will be re-opened, by an operation which is just 
the reverse of that described above. 

94. Another Tandem, Two-button, Snap Switch is illustrated 
in Fig. 76. Although the mechanism of the switch in Fig. 


Binding 

Post 

Stationary 
Contactor-.. 


Composition 
Insulation - 


Meta! Strip. 


a: Push-Button 
. Movable Contactor 



"V , • ■ Cover-Holding- 
Porcelain ScrewHok * 


Fig. 76.—Top view, with cover removed, of tandem, two-button, single-pole, “feed¬ 
through” or straight-through snap switch. (Beaver Machine & Tool Co.) 


76 is different from that of Figs. 73 and 74, the same general 
effect as that which is described in Sec. 93 is produced by 
pushing the buttons. A detailed explanation of the operation 
of the mechanism of Fig. 76 is described below. 

Explanation. —The switch as shown in Fig. 76 is open. The spring, 
S, has one of its ends secured to the movable contactor, B, and the other 
end secured to the metal strip, E, which carries the push-buttons. When 
the switch is in the open position (Fig. 76), the spring being under tension, 
pushes downward and to the left on the movable contactor, B; and, at 
the same time, it pushes upward and to the right on the metal strip, E. 
This spring pressure holds B in the position shown. B is pivoted at its 
center. 

By forcing the upper push-button downward, that end of the spring, 
S, which is secured to the metal strip, E, is also moved downward. This 
downward movement of the spring-end further compresses the spring, 










































Sec. 95] 


LIGH TING-S WITCII CON STRUCT 10 N 


53 


thus increasing the tension therein. Also, this downward movement of 
the spiing-end changes the direction of the force which the spring exerts 
on the movable contactor, B. When the spring-end which is carried by 
E has moved downward until it is below a horizontal line through the 
point w here the other end of the spring is secured to B, the force on B is 
upward and to the left. As soon as the direction of the force on B 
becomes upward, B rotates with a snap action in the right-hand direction 
until the ends of B are in contact with the stationary contactors, C, 
whereupon the switch is closed. After this rotation, the spring is again 
in the same relative position w r ith respect to B and C as it was before the 
switch was closed. The switch may be re-opened by a reversal of the 
above-described operation. 

95. The One-button Door Switch of Fig. 77 is designed for 
installation in a door-jamb (see Div. 8), so that opening and 

Switch- 




TL-Siole View Wi + h Porcelain Broken Away To Show Mechanism 


Fig. 77.—One-Button, single-pole door switch (List No. 2355, Bryant Electric Co.) 

closing the door operates the switch. The switch, as shown 
(Fig. 77) is closed. Pressing downward on the button rotates, 
with a snap action, the movable contactor upward about the 
pivot, D, thus opening the switch. When the pressure on 
the button is released, the switch snaps closed. The operation 
of this mechanism is explained below. 















































54 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


Explanation. —The switch-blade snap-movement which occurs in the 
operation of the switch shown in Fig. 77 is identical with that which 
is described under Sec. 92 in connection with Fig. 72. That is, when the 
button (Fig. 33-/7) is pushed downward, the upper end of the switch¬ 
spring, S, is rotated and compressed—as explained in Sec. 92 —until it 
acts upward on the movable contactor, B, thus rotating B with a snap 
to the open position shown by the dot-dash line in Fig. 77-/7. When B 
is rotated to the open position, the tendency of the switch-spring, S, is— 
just as in Fig. 72—to hold it in this position. However, when the pres¬ 
sure on the button is removed, the tension in the operating-spring, O, 
which was compressed when the button was forced downward, overcomes 
the tendency of S to hold B open, and acts to push the button upward. 
Consequently, the switch is closed with a snap when the pressure on the 
button is removed. In other words, the operating-spring (0, Fig. 77-/7) 
operates the switch—when the button-pressure is removed—in essentially 
the same manner as when button D, (Fig. 72-/7) is pushed with the finger. 

This type of switch is also made so that when the button is held “in” 
the switch is closed, and when the button is released, it is opened. 

96. The Operation Of Momentary-contact Snap Switches 

(Figs. 78 and 79) is similar to that of the door switch (Sec. 95) 
in that each contact remains closed—or open—only while 
the push-button is held in. Momentary-contact snap 
switches are made in two different types: (1) Those wherein 
the switch is normally open, so that when the button is pressed 
inward, the movable contactor rotates, with a snap action, 
to the closed position. Then when the pressure on the button 
is released, the movable contactor rotates in the opposite 
direction to the open position. (2) Those wherein the switch is 
normally closed, so that pressing inward on the push-button 
opens the switch and removing the push-button pressure 
closes it—both the closing and opening operations occurring 
with a snap action. Some’ momentary-contact snap switches 
are so made (Fig. 79) that two switches, each having its 
own push-button, are mounted in the same porcelain cover. 
Thus, two separate circuits may (Div. 8) be controlled from 
the same location. The operation of the mechanism of a 
momentary-contact switch is explained below. 

Explanation. —The normal position of the mechanism of a momen¬ 
tary-contact switch (porcelain casing removed) is shown in Fig. 78-7. 
The same mechanism with the movable contactor and the switch spring 
removed is shown at 77. The ends, E x and E h of the switch spring, 
which is carried by the shaft, S, hold the switch in its normal position 


Sec. 96] 


LIGHTING-SWITCH CONSTRUCTION 


55 


shown at I, as follows: The end of the switch spring, E h tends to produce 
right-hand rotation of the arm, A, about shaft M as a center. As shown 
at 11, the arm, A, is prevented from rotating to the right by the ends of 
the operating spring, O. The other end, E 2 , of the switch spring (Fig. 


Ena/s 0f t Switch 
• Spring \ 

\ \ 
"Xr, i Arrn \ _ 

Em A />Ez 



Push-Button 


o 



Notch\ 

Movable 

- -Contactor ! 
Shaft 


Arm 
Shaff . 


Operating 
Spring ' 


1-Normal Position 


... - Stationary 
Frame 



Operating 
’’ Spring 


n- Normal Position, Switch 
5pring And Movable 
Contactor Removed 


Movable- Contactor 
Shaft 


Arm 
Shaft - - 



IE-Position Just Before Rotation Of N ~Position Be 
Movable Contactor Occurs. (Switch Movable Con- 1 
Spring And Movable Contactor Removed) 


r ore Rotation Of 
•actor Occurs 


Fig. 78.—Showing operation of momentary-contact snap-switch mechanism. (Hart 

& Hegernan Mfg. Co.) 


78-/) tends to produce left-hand rotation of the movable contactor, B 
(Fig. 80) by pushing to the left on the lug, L—L is rigidly fastened to B. 
Left-hand rotation of B is prevented by another lug, D —which is also 
carried by B —engaging in a notch, N, (Fig. 78-//) in the stationary 
frame, F. 



























































































































56 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


When the push-button, C, is pushed downward, the arm, A, is rotated 
to the position shown in III and IV. As shown in IV, the lug at the 
upper end of A spreads the spring-ends, E\ and E 2 , apart, thus tending 
to rotate B to the right and at the same time increasing the tension in the 



Fig. 79 .—Showing operation of nomentary-contact snap-switch mechanism. (Two 
mechanisms are shown mounted back to back, thus two switches may be contained 
within a single porcelain casing. {Hart & Hegeman Mfg. Co.) 


switch spring. (When there is no force exerted on the switch spring 
the normal distance between the ends, E L and E 2 , is approximately equal 
to the width of the lug, L.) Rotation of B cannot yet occur because of 
lug H, (Fig. 78-1V) which is carried by B, striking lug G, which is on arm 

A. When A is rotated to the right a 
little farther than is shown at IV, H 
slips over G, and the tension in the 
switch spring causes a snap-action 
rotation of B to the position shown 
in Fig. 79-7 and 80-77. 

When the pressure on the button 
is released, the operating spring, 0, 
which was compressed when the but¬ 
ton was pushed inward, causes A to 
rotate to the left (Fig. 79-77). Arm 
A, thus pushing against Ei, tends 
to produce, through E 2 and L, left- 
hand rotation of B. However, B 
cannot yet rotate because of 77 striking G , as in Fig. 79-77. When A 
rotates a little farther to the left than shown in 77, G slips off of 77, and 
the switch-spring ends, E x and E 2 , rotate B with a quick snap action back 
to the position shown in Fig. 78-7. 

The general shape of the movable contactor, B, is illustrated in^Fig. 80, 


.Circuit Wires 



TClosed Position I'Open Position 

Fig. 80. —Illustrating the general ar¬ 
rangement of the movable contactor of a 
momentary contact switch. 






















































































Sec. 9G1 


LIGIITJNG-SWITCH CONSTR UCTION 


oY 



Porcelain Base 


Movable 

Contactor 


Bindjng 

Post-> 


Stationary 
Frame - 


Ratchet Case 


w 

■i'Rr 

I ///.Vi 

/ I / // 
i / '/ »'/ 


Operating 5pring 


Cord 

Guide 


Porcelain Base 


Holding-Screw 
X Hole 


Stationary 

Contactor 


Cord Guide 


Stationary! 
Frame ! 


Ratchet 


Holding''' 

Screw 

Hole-'' 


SO 

m 


)\ 

_l_1_ Ld 





* l - ■ 




E-Bottom View 


Fig. 81.—Ceiling-type, pull switch with cover removed. ( Bryant Electric Co.) 
































































































58 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


97. The Switch Mechanism Employed For The Snap 
Operation Of The Pull Switch of Fig. 81 is the same as that 
described in Sec. 89 in connection with Figs. 65 and 66. 
However, the shaft-rotation necessary to cause the operation 
of the switch mechanism is, in the pull switch (Fig. 81), 
produced by pulling a cord or chain, instead of by turning a 
button as in Fig. 65. Pulling the cord, C, rotates a ratchet 
mechanism contained in the ratchet-case, R, and at the same 
time winds up the operating spring, 0. The ratchet mech¬ 
anism engages the switch shaft and causes it to rotate far 
enough to operate the snap-switch mechanism. When the 
cord is released, the operating-spring, 0, unwinds, and rotates 
the ratchet-mechanism in the opposite direction, so that it is 
again in readiness to engage the shaft for the next operation. 

98. Various Operating Mechanisms Are Employed In 
Toggle Switches (Fig. 82). See Sec. 32. The method of opera- 


Btnchng 
Screw ... 


Me fa I Face Plate\ 
& 



Stationary Contactors 
Fig. 82. —Flush-type toggle or tumbler switch. 


Lever Rocks 
In This Slot 


Movable 

Contactor 


Porcelain 

Casing 



-■Toggle Lever 


•r Movable 
Contactor 


Stationary 

Frame 


Fig. 83. —Illustrating operation of 
toggle or tumbler snap switch. 


tion of one type of toggle switch may be understood by a con¬ 
sideration of Fig. 83. Pushing the handle, H, of the toggle lever 
backward and forward produces exactly the same effect as alter¬ 
nately pressing the buttons of the switch described in Sec. 92. 

99. Snap Switches Are Manufactured In Several Different 
Forms. The more general forms are: (1) Surface. (2) 
Flush. (3) Pendent. (4) Straight-through. (5) Canopy. 
Various applications of each of the above-listed forms are 
discussed in the following sections. 

Note.—Snap Switches, Which Embody The Various Types Of 
Operating Methods Previously Described Herein, Are Manufac¬ 
tured In Different Forms as outlined above. The types of operating 



















































































Sec. 100] 


UGH TING-SWITCH CONS TR UC TION 


59 


methods as applied to different snap-switch forms (Figs. 84 to 100 inclus¬ 
ive) are outlined in Table 100. The third column of Table 100 gives the 
number of the illustration wherein each of the various forms is illustrated. 



Fig. 84.—Rotating-button, surface snap switch. (General Electric Co.) 


100. Table Showing Different Forms In Which Snap 
Switches Of The Various Types Of Operating Methods Are 
Manufactured. 


Type of operating ' 
method 

Form 

Illustrated in 
Fig. No. 

Rotating-button. 

Surface 

Flush 

Canopy 

84 

85 

98 

Push-button. 

Surface 

Flush 

Pendent 


86 

87 

24 and 95 ] 
96 

99 


Straight-through 

Canopy 

Pull-chain or cord. 

Surface 

Ceiling 

Wall 

22, 81 and 88 
89 


Canopy 

100 

Tocrcrle. 

Surface 

Flush 

* 

90 

91 

v - , feo . 

Straight-through 

97 





























































60 LIGHTING CIRCUITS AND SWITCHES [Div. 2 

101. The More General Application Of Surface And Flush 
Snap Switches (Figs. 84, 85, 86, 87, 88, 89, 90, and 91) is for 
mounting on the wall near the entrance-door of a room or 




Switch Plate 
Indicating Slot 



< 2 > 

Operating Button 


Mu/tsmuw; 



I-Square Type I-Round Type 


Fig. 85.—Rotating-button, flush snap 
switch. ( General Electric Co.) 


Fig. 86.—Push-button, surface snap switches. 
{Cutler-Hammer Mfg. Co.) 


hallway for the control of laijips which are within that room 
or hallway, or for the control of lamps within a room or hallway 
adjacent thereto. Pull-chain, ceiling- and wall-type, surface 
switches are generally used for controlling lamps which are 


Binding f t —) 
Screws 


Sub-Plate 


$ 

■o 

C. 

n: 



Porcelain 

Casing 



Fig. 87.—Push-button, flush Fig. 88.—Pull-chain, ceiling snap switches. {Bryant 

snap switch with switch plate Electric Co.) 

removed. {Bryant Electric Co. 


mounted (Fig. 92) at a considerable height above the floor. 
This method of control of such a lamp-installation will usually 
require less wire than that for a pendent switch, or a rotating- 


































































































Sec. 101] 


LIGH TING-S WITCH CONSTR UCTION 


01 



Fig. 89. —Pull-chain, wall snap 
switch. {Bryant Electric Co.) 


Toggle-Lever Handle - •. 



1' ig. 90.—Toggle or tumbler surface snap 
switch. 


Switch Plate-. 



Screw For Securing 
Switch Plate, To Sub-Plate 


Toggle-Lever Handle 





High Ceiling 

- Pull- Chain, 
Ceiling,Surface 




l 



Fig. 91.—Toggle or tumbler flush snap switch. 
{Hart & Hegemon Mfg. Co.). 


Fig. 92. —Pull-chain ceiling snap 
switch used to effect a wire saving 
by eliminating a double-run of wire 
to a location which could be reached 
from the floor. 

































































































62 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


or push-button switch, which is so mounted that it may be 
reached from the floor. 

Note.—What Is Essentially Two-location Lamp-control May 
Be Provided By A Pull-cord, Ceiling Single-pole Snap Switch as 
suggested in Fig. 93. At a small cost many of the advantages of a set of 
three-way switches can be secured by placing the upstairs hall light on a 
ceiling pull-cord switch, so placed that the cord may be conveniently 
reached both upstairs and downstairs. Where the cord cannot be 
dropped directly from the second floor ceiling to the first floor, the cord 
can often be carried along the wall of the stairway, using small screw eyes 




Fig. 93.—Pull-cord, snap switch, S, so mounted that switch may be operated from 
two floors by pulling the cord or chain, C. 

Fig. 94.—Showing how an extension may be made for a pull-socket so that a wall 
bracket lamp may be controlled from door. A washer, W, is secured to the end of the 
cord to prevent its slipping through the screvr-eye. Often bell cranks can be profitably 
employed at each location where the cord direction changes, instead of the screw eyes 
as above shown. 

as guides. In Fig. 94, screw eyes are fastened in the baseboard and in the 
door facing as shown. A string, which is connected to the pull-cord 
of the socket, is guided to the door by the screw-eyes. The wall lamp 
may then be controlled from the door. 

102. The Most-frequent Use Of Pendent Snap Switches 

(Fig. 95) is, probably, for the control of a single lamp, or of 
several lamps on one fixture, which are mounted at a con¬ 
siderable distance above the floor. The total installation-cost 
of a pendent switch is usually greater than that of a pull-chain 
switch, but less than that of a surface or flush switch mounted 







































































Sec. 103] LIGHTING-SWITCH CONSTRUCTION 


63 


on the side-wall. Pendent switches may sometimes be used 
advantageously instead of pull-chain switches in locations 
where the pull-cord of a pull- 
chain switch would not hang 
vertically in a straight line from 
the switch. 


Wires 


Note.—Probably 
STALL ATIONS, T H E 


For Most In- 
PlJLL-CHAIN 
Switch Is Preferable because of 
its lower installation-cost and the 
fact that the chain or small-diameter 
pull cord which it requires casts 
a smaller shadow than does the lamp 
cord and switch of the pendent-switch 
arrangement. Probably, also, the pull- 
chain switch is the more sightly and 
involves the lesser maintenance cost. 



Wires 


Metal 
Covers-■ 


Operating 

Duttons. 



1-Tandem-Button, 
Single-Pole 


I-Parallel Button, 
Momentary Contact 


Fig. 95. —Push-button pendent snap 
switches. (Bryant Electric Co.) 


103. The Use Of Straight-through Snap Switches (Figs. 
96, and 97) is confined almost wholly to the control of those 



I-Gomposition Shell 



3-Brass Shell 



Fig. 96.—Push-button straight-through snap switches. (Cutler-Hammer Mfg. Co.) 


devices such as floor lamps, table lamps, flat-irons, toasters, 
percolators, soldering irons, small motors, and the like, which 








































































































































04 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


Composition 

Shell- 


Toggle - 

Lever 

Handle- 


are served by a flexible cord. The straight-through switch 
may be in stalled anywhere on the flexible cord. For those 

devices mentioned above, which 
are not ordinarily equipped 
with switches, a straight- 
through switch installed on 
the cord near the device, pro¬ 
vides a convenient control- 
location therefor. 


II-$wi+ch Anol Botse 


^. Holding 

Screws 


Insulating 

Composition 


Outline Of 
Canopy Shell 1 




EL Cotp 



Fig. 97.—Straight-through toggle 
snap switch. The operation of this is 
substantially the same as Fig. 83. 
(List No. 3000, Bryant Electric Co.) 


Operating 

Button 


Fig. 98.—Rotating-button canopy switch. 
(Bryant Electric Co.) 


104. The Use Of Canopy Switches (Figs. 98, 99, and 100) is, 

as the name implies, for the control of lamps or fixtures which 



Fig. 99. —Push-button canopy switch for wall canopy, showing installation and connec¬ 
tions. 


are provided with a canopy. Since they are installed on the 
inside of the canopy (Figs. 99 and 100) practical considera- 











































Sec. 104] 


LIGHTING-SWITCH CONSTRUCTION 


05 


Fig. 



. ■ ■Pipe Strap 


Pull-Chain--- 


Switch 

Cover 


Switch 

Wire 


Switch 

Wirp 



Conduit-‘ 


Canopy- 


Fixture- 
Supporting 
Chain' •. 


Pull; 

Chain 


L Pul I-Chain, Canopy H-Pull Chain.Canopy Snap Switch 
Snap Switch Installed Inside Of Canopy 

100.—Pull-chain, canopy snap switch for ceiling canopy. (List No. 655, Bryan t 


Electric Co.) 


9 9 


PUSH-BUTTON SWITCHES 

\^-\P-Mains 


Jr 


pr 

9 


"Shunt- 




js— , 


9 © 


9-- 


Shunt" 


9 9 


6 S> i^i 




I*3*Way Connections 

I U- -^Branch 

MMff 

9 J [9 9 


H- 3-Way Hot-Leg 
(Carter System) 





Maths-' - 

K-S.P_ flr-p.p S hunt 
Connections. Connections. — 


4-Way 


3Wby 


Shunt" 

Y-4-W ay Connections 
ROTARY FLUSH SWITCHES 


Mains- 



1ZT Double-Pole 
Connections 

? 


2E-3-Way Connections 


Line v 

g~3 


4 

cr~d 



Line-- 


1 


Slir-2-Circuit Electrolier 
Connections 


M 


^ ej 


tr~r> 



3X-3-Circuit Electrolier 
Connections 


I 


m 


MainsL 


del 

4-Vfai 


a 




e-'-e 


3'Wai^ 



X-4-Way Connections 


Fig. 101.—Flush snap switch wiring diagrams. ( The Hart Mfg. Co.) 


5 




















































































































66 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


tions necessitate that they be small and compact in 
construction. Their rating seldom exceeds 6 amp. at 125 
volts. 

Note.—Various Snap-switch Wiring Diagrams are shown in Figs. 

101, 102, 103, 104. 

± ToS? Z ID 




I-Single-Pole Push ff-Single-Pole Types. 

Dutton.Types B.P&Y O And R" ^ B.P, Y.OAndR 

+ Four-Way-- > ^ Three^ ay.. 

Three-. HZ > 

Way 


ET-Double- Pole. Types 
B,P,0 And R" 





°L 
I 2o 


-O 


F 


V-Three-And Four-Way. 
Types‘K TV And'0* 


taSSS-mtadfbtf SH-tOra.it Electrolier. 
Cat.£460,M9Z,2625 8c lllA ' Conn “t'“™ : U&E.I,Off- 


I 


°L I 



W-l Circuit Electrolier. 
Connections:!, Off, 2,Off. 
Cat.2628 








-o 


K-2-Circuit Electrolier. 
Connections-l,0ff,l And 2,Off. 
Cat. 2629 


X- 1- Circuit Electrolier. 
Connections:!,! And 2,Off. 
Cat. 2630 


°L Z -^r-©“ 
C>3 \oJ-Q- 


1- 



L 2°V-0-i 

\oX^T 


l 


ITZP^r 
P l 3o A . 


-Or 


Connections: 1,18:2,1 &2 &3,0f f. 
Cat. 2461,2493,2627 And 2210 


XK- 2- Speed Fan Motor. 
Connections: 1,2,Off. 
Cat 2631 


-o—* 


M-3-Speed Fan Motor. 
Connections: 1,2,3,Off. 
Cat. 2632 


*r 


,L 2A 




KqLAU- 


XK-Duplex Type “D" Cat. 2639. 
Connected As Two Single- 
Pole Switches. 

Siny/e- 


XY-Duplex Type D" Cat. 2639. 
Connected As A Two-Circuit 
Electrolier. 


-O—i 


°l — \J m i 

A 7 rUl _ (7X _ 


\j_—rtr - 


<L 


Pole And" 
Three-Way 


XM-Duplex Type D“ Cat. 2709. 
Two Single-Pole Switches 
With Separate Feeds 



ton 

'ee-Wau—W 


Three-Way-* 


XH-Duplex Type D. 
Cat. 2640 & 2745 


J —°1 

— VjL Iq C- qJ 


XK-Duplex Type D Cat. 
XM-Duplex Type "D" Cat. 2710. 2738,2742 And 2743 

One Single-Pole And One Three- 
Way Switch With Common Feed r ' 


J l°V 

-©-i 

--roLlo^r 

-XoL 2cyC 

-©- 



Zh 


o| ip\ 




L 3 o, 


T 


-O-J 


XX-Duplex Type D'Cat. 2740 XXhDuplex Type D Cat 2741 'ypeuvxxT.c/ 

Fig. 102.—"Wiring diagrams for flush switches. ( Bryant Electric Co.) 


105. A Circuit-connection Classification Of Snap Switches 

may be made according to the number of conductors which 
may be disconnected by them, and according to the sequence 
or method of making or breaking the several connections, as 
follows: (1) Single-pole. (2) Double-pole. (3) Three-pole. 
























































































































Sec. 106] 


LIGHTING-SWITCH CONSTRUCTION 


07 


(4) Three-way. (5) Four-way. (6) Two-circuit electrolier. 
(7) Three-circuit electrolier. (8) Series-parallel. Several of 
the more-commonly used circuit connections and the arrange¬ 
ment of the switch current-carrying parts (Sec. 80) for obtain- 




yi3v- 

L l„* 


-o- 


L L * 

AP 


rh 


I-Duplex Type'D" Cat. No. 2746. 

.-Duplex With Common Feed. 


+ —T 

E- Duplex Type “D" Cat. No. 2739* One 
Single-Pole And One 2-Circuit 
Electrolier Switch With Common 



-0 - 




o- 


-©— 


Feed. 


U-Duplex Type D 
Cat. No. 2737. 


14 


I?-Duplex Type “D" Cat. No. 2747. 


' < '--!25 Volt Line 

Sr Cat. No. 413 Double-Pole 
Ready Wired Bull's Eye Z 
Combination. 


"Cj o 


6® 



< & 
■s> 


■Lamp 
Lined, 


Three-Way 

Switch 

fin Upper 
Hall. 


H Four-Wau 

y 


Switch If 
<• Desired ; 


Chandelier 
In Lower 
Hall 




725 Volt Linei 


Lamp-- 




o 


T 


Light 
In 

Upper*® 
■Hall 


Three-Way Switch 
h Lower Ha ll 

_, AC" 


LB 


<3 


> c: >> 
- a.tr 


VII- Cat. No. 465 Double-Pole Type "0” 
Push Switch, Or Cat. No- 469 
Double-Pole Rotary Flush Switch 
Lock Type. 


- -K. ^ ± 

^ i 

O <b 

.t-* J* 
C C ^ 
^ I- 

YI-Electrolier Operation of 

Lights That Are Controlled K ^ 
From Two Or More Points. 


If 



'■'•12.5 Volt Line Lamp- 


IE-Cat. No. 413 Ready Wired 
Bull's Eye Combination 
Wired Single-Pole. 


& 


6"o- 


o 

o 

o 


ZH-Two Cat. No. 495 Three-Way 
Type “0” Push Switches. 

Three-Way Switc hes .. . 

'aired? 


O Ch 


125 Volt A 
Line 


14 


WFP 


Cat. No 427 
'■Lamps’- 


??? 



Lamp . _ 
p j^ /25 Volt Link - Y 

X-Cat No. 465 Or 469, Wired 
Single-Pole. 


E 


Xl-Wiring Diagram To Make Three- 
Way Switches Indicating. The 
Lamps In Both Bull's Eye 
Receptacles Are Lighted When¬ 
ever The Circuit Is Closed. 



XII-One Cat. No. 495, Three-Way Type‘0" 
Push Switch And One Regular 
Three-Way Switch- 


Fig. 103.—Wiring diagrams for flush switches—continued. ( Bryant Electric Co.) 


ing them are discussed in the following sections (see also 

Div. 1.) 

106. A Single-pole Snap Switch Has One Movable Con- 
tactor And Two Stationary Contactors (B and C, Fig. 105), 






































































































































LIGHTING CIRCUITS AND SWITCHES 






511" Double-Pole 


Circuit No. 2 Circuit N o. 1 

Circuit No 2 / ~~~ \ Circuit No. 1 

3X-Double-Pole Double-Throw 
Connected As Two Sinqle- 
Poie Switches. 



XJ-Triple- Pole 



ConnectionS-,1, 2, 
1 And 2, Off. 



H-2-Circuit Electrolier. 
Cdnnections;l, Off, 
2, Off. 1,1 And 2, 1, Off. 



Yl-2'Circuit Electrolier. 
Connections; l,Off, 

1 And 2, Off. 



Circuit Electrolier. 
Connections; 1,1 And 
2, 1 And! And 3, Off 



X: Electrolier And 3'Speed 
Fan Motor Connections; 
1,2,3, Off. 



XII'Electrolier And 2-Speed 
Fan Motor. Connections; 
1,1. And 2, Off. 1,2, Off; 



JQllrDouble-Pole Heater 
Switch .Operates 
High, Medium, Low 
And Off. 


-^LTLTLf OJLP- 
~ \ % 


JI?-Sinqle-Pole Heater 
Switch. Operates 
High, Medium, Low 
And Off. 


Fig. 104.—Wiring diagrams for surface switches. (Bryant Electric Co.) 











































































Sec. 107] 


LIGIi TING-SWI TCI! CONS T R UC TION 


60 


Ho/e For 
Fastening 
Screw -... 


Blade Or 
Movable 
Contactor 


so arranged that when the blade, or movable contactor, B , is in 
one position (Fig. 106-/) it does not touch the stationary 
contactor, C. In the other position (Fig. 106 -II), the blade, 
B, touches both of the stationary contactors, C, and current 
may then flow through the switch from one wire to the other. 

The current-carrying parts of 
single-pole, flush snap switches 
are arranged in essentially the 
same manner as those of the 
surface switch. 

107. “Double-deck” Is A 
Descriptive Term Which Is 
Applied To A Surface Snap 
Switch when the switch has 
two movable contactors (.LM 
and UM, Fig. 107), one of 
which is located above the 
other. That is, the two mov¬ 
able contactors of a double 



Stationary 

Contactor 


Terminal 

Screw 


I-Top View Of Assembly. 
Cover And Handle Removed 


•Button 

Handle 



Movab/e 

Contactor. 


Bindina 
Post 


Blade Or Movable Contactor 
Circuit Wires 


Stationary 
Contactors ... 


5fa tionary Con tac tor 


Porcelain Base 

E-Assembly With Cover Removed 

Fig. 105. — Single-pore, surface snap 
switch. ( Trumbull Electric Mfg. Co.) 



.■Circuit Wires*'. 



I-Rosition 1. Blade 
Not Touching 
Stationary Contactors 


I- Position 2. Blade 
Touching Stationary 
Contactors 


Fig. 106.—Circuit connection of single¬ 
pole snap switch. 


deck, surface snap switch lie in two parallel planes which 
are perpendicular to the switch shaft. These two movable 
contactors may, or may not be insulated from each other. 
Each movable contactor of the double-deck switch has 
one or more stationary contactors (LS and US, Fig. 107), 
located in its respective plane. These stationary contac¬ 
tors may or may not be electrically-connected to each other 
by an internal shunt. Double-pole, three-pole, four-way, 
electrolier, and series-parallel surface snap switches frequently 
employ the double-deck construction. See following sections. 




































70 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


Some switches employ three decks and are then of three-deck 



IS. Diciqram Of Connections YHI-Diagram Of Connections 
Fig. 107.—Illustrating arrangement of a double-deck, double-pole, surface snap switch. 

construction. Theoretically , switches may employ any number 

of decks or be of multi-deck construction. 


Porcelain 



Fig. 108.—Double-deck snap switch 
for highly inductive circuits which is 
provided with barriers of insulating 
fibre to prevent a dangerous arc from 
being formed when the circuit is 
broken. 


Note.—Although The Movable- 

AND-STATIONARY-CONTACTOR ARRANGE¬ 
MENT Of Flush Snap Switches Of 
The Oscillating-blade (Sec. 24) 
Type Is Frequently Such As To 
Comply With The Above Definition 
Of A Double-deck Switch, the term 
“double-deck” is not usually applied 
to oscillating-blade snap switches. It 
is usually applied only to revolving- 
blade switches. 

Note.—For Use On Highly- 
inductive Circuits, Multi-deck 
Snap Switches Are Frequently 
Provided With Barriers of insu¬ 
lating fibre (Fig. 108). Thus, discs of 
insulating fibre are placed, one above, 
one below, and one between each deck, 
thereby preventing the e.m.f. of self¬ 


induction from establishing a dangerous 
arc upon breaking the circuit by opening the switch. See Sec. 130 for 
'‘barriers” for knife switches. 




























































































Sec. 108] LIGHTING-SWITCH CONSTRUCTION 


71 


108. Double-pole Snap-switch Construction Usually Con¬ 
sists Of Two Movable Contactors And Four Stationary 
Contactors (Figs. 109, 110, and 111). The double-pole 



Fig. 109.—Illustrating principle of double-pole snap switch. 



Fig. 110. —Showing one arrangement 
of a movable contactor in a double¬ 
deck, double-pole, revolving-blade snap 
switch. 


Upper-Deck 



Fig. 111.—Showing arrangement of sta¬ 
tionary contactors and binding-posts for a 
double-deck, double-pole, revolving-blade, 
snap switch. 


revolving-blade type of switch is ordinarily constructed in the 
double-deck arrangement as illustrated in Fig. 107. The upper- 



















































































72 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


deck movable contactor ( UM , Fig. 107-7) is at right-angles to, 
and insulated from the lower-deck movable contactor, LM. 
For each movable contactor there is one pair of stationary 
contactors, so arranged that when the switch is in the position 
shown in Fig. 107-7, the upper-deck stationary contactors, US, 



I-Closed Position 



I-Open Position IT-Closed Position IT-Open Position 


Fig. 112. —Showing circuit-connections of double-pole surface snap switch. (Begin¬ 
ning with I, four operations causes switch to resume position I. Current path is indi¬ 
cated by arrows.) 


touch the upper-deck movable contactor, UM, also, the lower- 
deck stationary contactors, LS, touch the lower-deck movable 
contactors, LM. Thus, the switch is closed, and current may 
flow as indicated by the arrows in the diagram of connections, 



} Line--> 

i 

7 

u-. J 


/ 

! •!' 

y -vr 

§ 

1 

; 

■N 

/ 

/ 

j 'Sc 

1 

j 

1 


F;. 



Porcelain Casing-^ 



^ -..-Loacf 

I-Closed Position 
(Top Button Up) 



F-Open Position 
(Top Button Down ) 


Fig. 113.—Illustrating circuit-connections of an oscillating-blade, two-button, double¬ 
pole, flush snap switch. 


IV. When the switch is in the position shown in Fig. 107-F, 
UM and LM do not touch either US or LS; the switch is open, 
both wires which connect to the load are disconnected 
from the line, and consequently no current can flow. The 
circuit-connections of the switch for four successive operations 
of the button-handle are shown in Fig. 112. The circuit- 






































































Sec. 109] 


UGHTING-SWITCII CO NSTR UCTION 


73 


connections for an oscillating-blade, two-button, double-pole, flush 
snap switch are shown in Fig. 113. 


109. An Arrangement Of The Current-carrying Parts Of, 
And The Circuit-connections For A Three-pole, Surface 
Snap Switch is shown in Fig. 114. It has three movable 
contactors, each being located in a separate deck. Therefore, 
it is a three-deck switch. For each movable contactor there 


are two stationary contactors which are located diametrically 
opposite one another and at the proper height or elevation 
to contact only with their movable contactor. That is, the 
upper-deck stationary contactors will contact only with the 
upper-deck movable contactor; the middle-deck stationary 




IT-Partial Sectional 
Elevation 


Fig. 114.—Positions and arrangement of current-carrying parts for a three-pole snap 

switch. 


contactors will contact only with the middle-deck movable 
contactor, and so on. The movable contactors are insulated 
from each other. Also, the stationary contactors are sepa¬ 
rated by insulation. The switch—which is a two-position 
switch (Sec. 41)—is shown in the closed position in Fig. 114-7. 
One operation of the handle rotates the movable contactors 
through an angle of 90 deg. to the open position at II. The 
next operation would cause another 90-deg. rotation and the 
switch would again be in the closed position as shown at 7, 
the movable contactors having been rotated 180 deg. from 7. 

110. A Typical Arrangement Which Is Employed In The 
Construction Of Three-way, Revolving-blade Snap Switches 
consists of one movable contactor ( B , Fig. 115-F) and four 
stationary contactors, C. Two of the stationary contactors 
are connected together by a shunt, S, within the switch. The 


































74 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


binding-post is usually omitted from one of the shunted 
stationary contactors. Thus, there are only three binding- 
posts on a three-way switch. As illustrated in the diagram 
of circuit-connections (Fig. 115) the movable contactor is, 


Line -Porcelain Traveler 

Binding-Post-, / Base Binding-Posts 



Switch 

Travelers. Stationary 

\ Contactors* 




V r Movable 

t Contactor 

I'First Operation I-Second Operation M-Third Operation BT-Fourth Operation 

Line Binding-Post . ■(f^.^N-Traveler Binding-Post 

Shunt Embedded In Switch Base-\\r> 

Stationary Contactor(Not A Binding-Post)- . 

Movable Contactor- 

V* Plan View Showing Arrangement 
Of Current-Carrying Parts 

Fig. 115. —Illustrating typical construction and circuit-connections of a three-way, 
surface snap switch. (.Arrows indicate possible current paths.) 


except during operation, always touching two diametrically- 
opposite stationary contactors. Therefore, there is always an 
electrical connection between a line binding-post and one or 
the other of the traveler binding-posts. 


Stationary 
Contactor (Mot A 
Binding Post) 




(A—Binding 


Shunt Embedded In 
Porcelain Casing .: 


O 

I Binding 
Posts. 




// 


'Ml 




Post 


Porcelain 
■i Casing ' 


7 / 



Movable 

Contactor 

4-'' f 


bd.. dyV. ^ . . 

T ——T .-.-4£4 —Bindma- 
Posts 


m ^7////z 


!<- 





% 




-Switch Travelers- 




''S 




Stationary 
Contactors 


Movable 
Contactors £ 


v 

Porcelain /, 
6 Casing w 



I-Posit ion A 
Top Button Down 


I* Position B 
Top Button Up 


TH" Diagrammatic 
Section 


Fig. 116. Positions and construction of a three-way flush snap switch of the oscillat- 
ing-blade type. (Arrows indicate possible current-paths. The black filled-in circle 
represents a push-button up or out. The white circle represents a push-button down 
or in.) 


Explanation. —One operation of the button-handle causes the 
movable contactor (Fig. 115) to rotate through an angle of 90 deg. 
If, then, with the first operation of the switch-handle, the movable 

























































Sec. 110] LIGHTING-SWITCH CONSTRUCTION 


75 


contactor is in the position shown at Fig. 115-7, its positions for successive 
operations will be as shown at II, III, and 7F. The possible current- 
path for 7 and 77 is the same as that for 777 and IV, although 
the movable-contactor in 777 and in IV has been rotated 180 deg., 
respectively, from 7 and from 77. It is a two-position switch (Sec. 41); 
one position is shown in 7 and 777, and the other position in 77 and IV. 

Note.—The Circuit-connections And Typical Construction- 
arrangement Of The Current-carrying Parts Of Three-way 
Flush Snap Switches Of The Oscillating-blade Type are illustrated 
in Fig. 116. The same circuit connections are herein provided as in a 
three-way surface switch (Fig. 115). 



I-Switch A, Position 1; Switch B, Position 1: Lamp Off 



1-Switch A, Position 2; Switch B, Position 1;Lamp On 



H-Switch A, Position Switch B, Position 2; Lamp Off 



H-Switch A, Position 1;Switch B, Position 2; Lamp On 


Fig. 117.—Showing possible circuit-connections effected by two three-way switches 

connected for two-location lamp-control. 

Note.—The Four Possible Circuit-connections Provided by 
Two Three-way Snap Switches Connected For Two-location 
Lamp-control is illustrated in Fig. 117. As shown at 7, the lamp is off. 
By operating switch A —practically all revolving-blade switches turn in 
right-hand direction only—77 results and the lamp will be on. Or, by 
operating switch B, IV results, and the lamp will be on. Similarly, by 
tracing out the circuit-connections provided by the other possible switch¬ 
blade positions, it will be evident how the lamp may, with either A or B in 
any position, be turned either on or off by either A or B. Although the 
diagram in Fig. 117, is shown for a three-way surface switch (Fig. 115), 
the principles outlined therein are essentially the same as those for a 
three-way flush switch (Fig. 116, see also Div. 5). 





















76 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


111. A Typical Construction-arrangement Of The Current- 
carrying Parts, And The Various Circuit-connections Through 
A Four-way, Revolving-blade Snap Switch are shown in Fig. 
118. The switch (Fig. 119-7) has four binding-posts. Each 
binding-post has two stationary contactors (Ci and C 2 , Fig. 
119-77), one located in the upper deck, and one in the lower 
deck. The two movable contactors are of the form shown at 
777 in Fig. 58. These two contactors (7? 1 and 7? 2 , Fig. 119), 
are located, one in the upper deck and one in the lower deck, 
and are insulated from each other. They are (Fig. 58-777) so 
shaped that each movable contactor always, except during 
operation, makes contact with two adjacent binding-posts. 
Successive operations of the’ switch causes the movable 



Operation 


Travelers- -.., L ower-Deck Movable Contactor .. 

+ Lower- . 
Deck A 
jMovable 
Confact- 
or- 



. Travelers 

H-Second 
Operation 


3K-Third 
Operation 


IV-Fourth 
Operation 



VI-Sectional 
Elevation 
A-B 


Fig. 118.—Positions of successive operations and construction of a four-way snap 

switch. 


contactors to rotate through an angle of 90 deg., as shown in 
Fig. 118. The possible current-paths through the switch are 
indicated by the arrows. 

Note.—Movable-contactor Positions Of Four-way, Oscillat- 
ing-blade, Flush Snap Switches are shown in Fig. 120. Four-way, 
flush snap switches provide the same circuit-connections as do four-way 
surface snap switches (Fig. 118, see also Div. 5). 

Note. —A Four-way Switch Is A Commutating Switch. That this 
is true will he evident from a consideration of the polaraties shown in 
Fig. 118. That is, in alternate positions, it changes the current direction, 
in the circuit feeding from it. In I and III the left-hand wire is positive 
( T) whereas in II and IV the left-hand wire is negative ( — ). 

Note.—The Eight-possible Combinations Of Switch-blade 
Positions And Circuit-connections Provided By Two Three-way 






















Sec. Ill] 


LIGHT! NG-SWITCH CONSTRZJCTION 


77 



'Lower-Deck 
Movable 
Contactor: 


'— Upper-Deck X 
Movable Contactor 


binding Poet. 


Porcelain 

base 



Lower-Deck 

Stationary 

Contactor 


Upper-Deck 
Movable 
Contactor ,> 


'Shaft 


ii 


Upper-Deck 
Stationary Contactor 

~J L ower-Deck \ 

J Movable 
Contactor 


binding 
Post■ . 


* u 


31-Siole View With Porcelain Ba^e Pcxr+iotlly Removeol 


Fig. 119.—Showing construction of four-way, surface snap switch. List No. 2183, 

Bryant Electric Co.) 


















































































78 


LIGHTING CIRCUITS AND SWITCHES 


[Dry. 2 


Switches And One Four-way Switch, Connected For Three- 
location Lamp-control are shown in Fig. 121. With the switches, A, 
B, and C, in the positions as shown at I, the lamp is on. By operating 
either switch A, B, or C, the lamp will be turned off as follows: (1) 
Operating A, II results. (2) Operating B, V results. (3) Operating C, IV 
results. Similarly, it can be shown that with any one of the combina¬ 
tions of switch-blade positions which lights the lamp (Fig. 121-7, -III, 
-VI and -VIII), one operation of either A, B, or C will extinguish it; and 
vice versa, if with any combination of positions, the lamp is off (II, 71 , 
V, and VII) one operation of either A, B, or C will light it. Thus with 
any one of the above eight combinations of switch-blade positions, the 
lamp may be turned either off or on by either switch A, B, or C (see also 
Div. 5). 




A-Top Button Down. B'Top Button Up. 

I-Single Contactor Switch 




C -Top Button Down. D"Top Button Up 
I* Double Contactor Switch 


Fig. 120.—Positions of four-way flush switches of the oscillating-blade type. 


112. Electrolier Snap Switches Are Made In Both The 
Single- And Multi-deck Types. Usually, two-circuit electro¬ 
lier switches have only one deck and three-circuit switches 
have two or more decks. Practically all electrolier switches 
are of the revolving-blade type (Sec. 23). A typical two- 
circuit electrolier switch and the circuit-connections provided 
thereby, is digrammed in Fig. 122. The switch (Fig. 122) is 
of single-deck construction, having one T-shaped movable 
contactor, and three binding-posts. Each binding-post 
carries one stationary contactor. For complete discussion of 
electrolier switch circuits see Div. 7. 

113. The Construction And Circuit-connections Of Series- 
parallel Snap Switches are fully described in Div. 7 . These 
switches usually employ a multi-deck arrangement. The 
movable contactor on each deck may be of either the T-, L-, oi¬ 
l-shape (Fig. 58). The binding-posts carry one stationary 
























































Sec. 113] 


LIGHTING-SWITCH CONSTRUCTION 


79 





Fig. 121.—Showing the various combinations of switch-positions and the circuit- 
connections provided thereby for two three-way and one four-way snap switch connected 
for three location lamp-control. (Arrows indicate current flow.) 






















































80 


LIGHTING CIRCUITS AND SWITCHES 


[Div 2. 


contactor or two stationary contactors one above the other, 
depending upon the desired sequence of circuit-connections. 



I-Posi+ionl: A And B Off 





Fig. 122. —Illustrating construction and 
circuit-connections of a two-circuit elec¬ 
trolier switch. 



Fig. 123.— Indicating dial for a rotating- 
button snap switch. (Hart Mfg. Co.) 


114. Snap Switches Are Made In Both The Indicating And 
Non-indicating Types. An indicating snap switch is one 




I-Indicating Disc With Slot In Cover 


F-Pointed Button With On” 
And “Off’’Stamped On Cover 


Fig. 124.—Showing various methods of construction of indicating surface snap switches 
. of the rotating-button type. 

which, when installed, has some externally-visible marking 
which indicates whether the switch is open or closed. A non- 


Switch Cover -. 


Switch 

Cover 















































































Sec. 115] 


LIGHTING-SWITCH CONSTRUCTION 


81 


indicating snap switch has no such marking. One method of 
construction which is frequently employed in indicating snap 
switches ot the rotating-button type employs an indicating 
dial, (I, Fig. 63) which is fastened to, and rotates with the 
shaft. It is marked with the words (Fig. 123) ‘'off” and 
“on” so that when the switch is closed (Fig. 124 -I) the word 
“on” is visible through a slot in the switch-cover. When the 
switch is open, “off ’’ is visible. Another method is shown in 
Fig. 124 -II ,. wherein a pointed button is used. The words 
“on” and “off” are stamped on the switch-cover, and so 
arranged that when the switch is closed, the button points 
to “on.” When it is open, the button points to “off” (see 
also Sec. 308). The on- and off-indications for a two-button 
push switch are usually provided by making the buttons of 
different colors, so that, say, when the white button is in, and 
the black button out, the switch is closed; and when the black 
button is in, and the white button out, the switch is open. 

115. Snap Switches Which Bear The Approval-label Of 
The Underwriters’ Laboratories have been inspected and 
have been found to comply with certain specifications, regard¬ 
ing both construction and operation, which have been formu¬ 
lated by the laboratories. These specifications are contained 
in detail in Standard For Snap Switches, a copy of which 
may be obtained from the Underwriters’ Laboratories, 207 
E. Ohio St., Chicago, Ill.; its cost is approximately $1.00. A 
brief outline of the operating requirements is contained in the 
following section. 

116. The Underwriters’ Laboratories Tests Of Snap Switch 
Operation consist of: (1) Overload test. (2) Heating test. 
(3) Endurance test. Each of these tests are briefly described 
in the notes below. For complete details of the specifications 
for these tests, see Standard For Snap Switches. 

Note.—For A Snap Switch To Comply With The Underwriters’ 
Laboratories Overload Test, the switch must—if it has a rating of 
10 amp. or less—operate successfully when tested with direct current 
at 150 per cent, of the rated ampere capacity at full rated voltage. For 
switches which have a rating in excess of 10 amp., this test is made at 
125 per cent, instead of at 150 per cent, of the rated current-carrying 
capacity. To “operate successfully” the switch must open repeatedly, 
arid without appreciable damage, the overloads just specified. 

6 


» 


82 


LIGHTING CIRCUITS AND SWITCHES 


[Dtv. 2 


Note.—For A Snap Switch To Comply With The Underwriters’ 
Laboratories Heating Test, the temperature of the switch-jaws, 
blades, and other current-carrying parts must not, when carrying con¬ 
tinuously the rated current, rise over 54 deg. Fahr. (30 deg. Cent.) above 
the temperature of the room in which the test is being conducted. The 
temperature-rise is determined by applying the bulb of a mercury ther¬ 
mometer to the current-carrying parts, and protecting the bulb from air 
currents by putty or other suitable means. 

Note.—For A Snap Switch To Comply With The Requirements 
Of The Underwriters’ Laboratories Endurance Test, it must, when 




Collar 

Ratchet 
Teeth-' 

Sleeve--* 



II-Dctail Of Spindle^ 
Enlarged View 

Fig. 125.—Machine for testing snap switches. (The switches which are under test are 

not shown in I and III.) 


slowly operated at a rate not to exceed 20 snaps per min. while carrying 
rated current at rated voltage, complete 12,000 snaps before failing. 
This endurance test is made with a power-driven test machine. The 
exact form of the endurance-test machine is not specified. The construc¬ 
tion and operation of a machine which has been found suitable for this 
purpose is explained below. 

Explanation. —A Snap Switch Endurance-test Machine, designed 
for testing switches of the revolving-blade type is shown in Fig. 125. 
The switches to be tested are mounted on the machine as shown at II. 
A non-inductive electric load, consisting of a group of incandescent lamps, 
is fed through each switch in series. The electric load on each switch is 





























































































Sec. 116] LIGHTING-SWITCH CONSTRUCTION 


83 


so adjusted that it is equal to rated current at the rated voltage of the 
switch. Then, when the driving mechanism operates, the switches are 
thereby opened and closed. The device is driven by a 2,000-r.p.m. fan 
motor, M. The whole mechanism is so back-geared that the spindles, S, 
which turn the switch-mechanism, rotate at about 4 r.p.m. 

Each switch is driven through the spindle, S, which is illustrated in 
detail in IV. There are two ratchet teeth on the end of the sleeve, 
which is held securely in the worm gear. When it is desired to remove 
any switch from the device or to discontinue the test, the collar may be 
raised with the fingers. This raises the driving shaft so that then the 
switch will no longer be rotated by the machine. Furthermore, this 
ratchet clutch permits the switch spring to operate the switch with a 
“snap,” and also permits the action of any “back-lash” which the 
switch may have. 

To prevent the porcelain switch bases from turning on the wrought iron 
base of the machine a block of wood is inserted under the base, as sug¬ 
gested in the picture. From this block of wood, wooden dowels extend 
up into the screw holes in the switch base. 

QUESTIONS ON DIVISION 2 

1. Make a sketch of a knife switch and name the various parts. 

2 . Under what two headings may the materials used in knife-switch construction 
be classified? 

3. What is the allowable current-carrying capacity per square inch of cross-sectional 
area for knife-switch blades? 

4 . Describe knife-sw r itch jaw construction. 

5. Describe a method of obtaining firm contact between blade and jaws of a knife 
switch. 

6 . What requirement must be met in fastening the jaws to the base? Give two 
methods of complying with this requirement. 

7 . By what means are the wires connected to front-connected knife switches? To 
back-connected knife switches? What is the point of connection sometimes called? 

8. When must connecting-lugs be used? 

9 . Name the different materials which are usually employed in the construction of 
the following knife-switch parts: (a) Base. (b ) Cross-bar. (c ) Handle. 

10 . Classify knife switches according to form. 

11 . What troubles frequently occur in knife switches? How may they be located and 
remedied? 

12 . Under what three headings may snap-switch mechanisms be classified? 

13 . Give the names of the current-carrying parts of a snap switch. 

14 . Name the principal types of the contactor mechanisms of snap switches and 
describe each. 

15 . Why are metal covers of snap switches lined with an insulating material? 

16 . Describe the basic principle of snap-switch operating-mechanism. 

17 . Explain the operation of one type of rotating-button snap-switch mechanism. 

18 . How may push-button snap switches be classified? 

19 . Explain the operation of the mechanism of a one-button, push snap switch. 

20 . Explain the operation of a release-catch mechanism in a two-button push switch. 
Make a sketch. 

21 . Explain the operation of a lever-mechanism for a two-button, push switch. Make 

a sketch. - 

22 . Make a sketch showing two different button arrangements which are employed in 

two-button, push-switch construction. 


84 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 2 


23 . Explain the operation of a momentary-contact switch. 

24 . Name five forms in which snap switches are manufactured and give the general 
uses for which each form is applicable. 

25 . Draw the wiring diagrams for the following snap switches, both for the surface 
and flush types: (a) Single-pole. ( b ) Double-pole. (c) Three-pole, (d) Two three-way 
switches for two-location lamp-control. (e ) Two three-way switches and one four-way 
switch for three-location lamp-control. (/) A two-circuit electrolier switch. ( g) A three- 
circuit electrolier switch. 

26 . Classify snap switches according to circuit-connections. 

27 . What is meant by the term double-deck as applied to snap-switches? Make a 
sketch to illustrate. Multi-deck? Draw sketch. 

28 . Show by sketch the internal circuit-connections and typical construction of each 
of the following types of switches: (a) Single-pole. ( b) Double-pole, (c) Three-pole. 
( d ) Three-way. (e) Four-way. (/) Two-circuit electrolier. 

29 . What device is used in snap switches which are to be used on highly-inductive 
circuits? Why? 

30 . Show by sketch all of the possible combinations of switch-blade positions of two 
three-way switches connected for two-location lamp-control, and the current-path for 
each combination. 

31 . Same as Ques. 30 for two three-way switches and one four-way switch connected 
for three-location lamp-control. 

32 . What is an indicating snap switch? A non-indicating? 

33 . Explain the indicating devices which are frequently employed in indicating snap- 
switch construction, for both the rotating- and push-button types. 

34 . With what three operation tests must approved snap switches comply? Explain 
briefly the requirements of each test. 


DIVISION 3 


UNDERWRITERS' REQUIREMENTS 

117. Compliance With The Regulations Of The National 
Board Of Fire Underwriters For Electric Wiring And Appa¬ 
ratus Is Usually Necessary if the building is to be insured 
against fire-loss. These regulations are known as the National 
Electrical Code (hereinafter abbreviated to Code). The 
Code has no legal force except in those municipalities where 
it has been legalized by statute. Many cities have regulations, 
that are based upon and are similar to the Code, which have 
been legalized by statute or ordinance, and which, in those 
cities, must be observed. 

118. The Code Requirements Which Are Treated Herein 

are only such as relate to the installation of switches, circuit- 
wires, and fuses for low-potential (600 volts or less) building¬ 
lighting circuits. Since practically all electrical devices which 
are on the market are approved by the Underwriters’ Labora¬ 
tories as regards design and material, it is ordinarily necessary 
for the installer to watch only the installation requirements of 
the Code. The following sections contain the more important 
Code (1920 Edition) requirements and recommendations 
which relate to interior switch and lighting-circuit installation. 

Note.—Certain 1923-Code Rules Will Probably Be Different 
From The Corresponding 1920-Code Rules. As this book goes to 
press (February, 1923), there is being circulated a bulletin which contains 
a number of proposed changes in the rules of the 1920 Edition of the 
National Electrical Code. This bulletin was prepared by the 
Electrical Committee of the National Fire Protection Association and will 
be submitted to the National Board Of Fire Underwriters at the March 
12, 1923 meeting in New York City, for the purpose of having these 
proposed changes incorporated in the 1923 Edition of the Code. At 
this time it is impossible to predict whether or not these proposed changes 
will be adopted but it appears probable that they will be. Therefore, it 

85 


86 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 3 


is likely that certain of the 1920-Code rules, which are now in effect and 
upon which this book is based, will be changed in the 1923 Edition. 
Attention is directed to some of these possible changes at various places 
in the book. In any event, one should consult the 1923-Code before 
proceeding definitely. 

Note.—An Approved Device is a device, a sample of which has been 
examined, tested, and approved for use, by the Underwriters' Laboratories. 
The Undeder writer s’ Laboratories is an institution maintained by the 
National Board of Fire Underwriters, the principal office and testing station 
of which is located at 207 E. Ohio St., Chicago, Ill. All approved 
devices and materials are so labeled with metal plates, paper stickers, 
or tags, which are furnished, to manufacturers of approved equipment, 
by the Underwriters’ Laboratories. 

119. Approved Knife Switches Are Plainly Marked With 
The Maximum Ampere And Voltage Rating for which they are 
designed (Code Rule 65 a). This marking (Table 120) must 
be so located that it can be read when the switch is installed. 
The voltage and the probable maximum load on the circuit 
must not exceed the voltage and ampere rating as stamped on 
the switch. A switch of larger rating than that of the circuit 
which it controls may, if the circuit is properly fused, (Sec. 169) 
be used, but it will usually be uneconomical. 

120. Table Showing Classification And Markings Of 
Knife Switches. (Code Rule 65a.) 


30 to 1,000 amp., inclusive 

Classification 

Markings 

125 V., D.C. or A.C. Only for switchboards and 
panelboards. (With or without fuses.) 

125 V.. . Amps. 

250 V., D.C. or 500 V., A.C. (Without fuses.) 

250 V., D.C., 
500 V., A.C. 

.. . Amps. 

250 V., D.C. or A.C. (With fuses.) 

250 V...Amps. 

500 V., A.C. (With 600-volt fuses.) 

500 V., A.C. 

... Amps. 

600 V., D.C. or A.C. (With or without fuses.) 

600 V. .. Amps. 




















Sec. 121] 


UNDERWRITERS’ REQUIREMENTS 


87 


30 to 1,000 amp., inclusive 

Classification 

Markings 

Triple-pole: With 125-volt spacings between blades. 
For use on three-wire systems having 125 volts 
between adjacent wires and not over 250 volts 
between outside wires. 

125 V...Amps. 

Triple-pole: With 250-volt spacings between blades. 
For use on three-wire-systems having 250 volts 
between adjacent wires and not over 500 volts be¬ 
tween outside wires. 

250 V...Amps. 


Above 1,000 amp. 


For switches of capacities above 1,000 amperes, the A.C. rating will 
generally be less than the D.C. rating, and in such cases the marking 
should indicate the ampere rating definitely as A.C. or D.C. The 
frequency in cycles should also be stated. 

121. Switch Bases Upon Which Live Parts Are Mounted 

(Code, Class D, Bases) must be made of approved non-com¬ 
bustible, non-absorptive insulating material, such as hard 
rubber, slate, marble, porcelain, fiber, etc. The design of the 
base must be such that it will withstand the most severe 
conditions which are likely to be encountered in practice. 

Note.—Screws For Supporting Bases which have an area greater 
than 25 sq. in. must be at least four in number. Holes for the supporting- 
screws must be so located ( A , Fig. 126) or countersunk (A + B, Fig. 127) 
that there will be at least 34-in. space, measured over the surface, 
between the screw-head or washer and the nearest live metal part. 
Screws (S, Fig. 126) which are located between parts of opposite polarity 
must be countersunk. Nuts or screw-heads on the under side of the base 
must be countersunk and sealed with a water-proof compound. 

122. The Spacings Between Knife-switch Parts (Code 
Rule 65c) must be equal to or exceed that shown in Table 123. 
The dimensions as given for break distances (Column 5, 
Table 123, and A Fig. 128) do not apply to quick-break attach¬ 
ments (Sec. 132) on switch mechanisms. 

Note.—The Minimum Allowable “Break” Or “ Between-parts- 
of-opposite-polarity” Distance Between Knife-switch Parts 






























88 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 3 


(A and B, Fig. 128, and Table 123) is taken as the shortest distance 
between any part of the switch-contact mechanism. That is, it is the 
shortest distance as measured between the metal blocks (contact-blocks) 
which carry the jaws, between the screw-heads or nuts at the hinge-jaws, 




• '- '/.-Screw Between Opposite 

; Polarities Must Be ■ ■ 
c\ -• Counter-Sunk .' ’ ■ 


ive Meta! 
Part-- - i 


Insulating' 
Base • ■ 


■ • ■ .Holding Screw-pi 


Fig. 126.—Showing Code requirements for distances between holding-screws and 
nearest live metal parts for switch bases. (If area of base exceeds 25 sq. in., at least 
4 holding screws must be used. Distance A must not be less than in.) 

or between the flared edges of switch jaws, depending upon various fea¬ 
tures of design and construction. Switches are frequently equipped with 
extensions (E, Fig. 173) for enclosed fuses of either the cartridge or Edison 
plug types. However, the switch spacings given in Table 123 should not 



Metal Part 
Nearest To Screw 

■Holding 
• Screw y 



-Break Distance- O 


jt- -Opposite-Polarity 
\ . v '.Distance.^:y\ 


Fig. 127. —.Counter-sunk holding- Fig. 128. —Measurements for minimum allow- 
screws for switch bases must be so able knife switch spacings. 

located that A 4- B is at least in. 

be applied to cutout bases, even though the cutout base is a part of the 
switch construction. For the minimum allowable distance between 
live metal parts of cutouts, the cutout is to be considered as a unit 
separate and distinct from the switch. 

123. Table Showing Minimum Allowable Knife-switch 
Spacings. Measurements are to be taken within the area of 



































































































Sec. 123] 


UNDERWRITERS' REQUIREMENTS 


89 


the switch base bounded by the contact parts of the switch 
mechanism (see Fig. 128). 


Mounting 

Maximum 

voltage 

Ampere 

rating 

Min. distance 
between metal 
parts of opp. 
polarity in in. 
(B, Fig. 128) 

Min. break 
distance in in. 
(A, Fig. 128) 

Switch¬ 
boards and 
panels only 

125 V. 

D.C. or A.C. 

30 

60 

1 

IK 

K 

l 


4 


IK 

l 



60 and 100 

l K 

IK 


125 V. 

200 and 300 

2Vi 

2 


D.C. or A.C. 

400 and 600 

m 

23^ 



800 to 6,000 

3 

2K 



30 

1H 

IK 

All 

250 Y. 

60 and 100 

2 K 

2 

other 

D.C. or A.C. 

200 and 300 

2K 

2 K 

switches 


400 and 600 

2 K 

2K 



800 to 6,000 

3 

2% 



- 

30, 60 and 100 

2 K 

2 


500 V. 

200 and 300 

2 K 

2 K 


A.C. 

400 and 600 

2K 

2H 



800 to 6,000 

3 

2K 


600 V. 

30 and 60 

4 

3 H 


D.C. or A.C. 

100 to 6,000 

4K 

4 


Note.—Switches Marked “250 V., D.C., Or 500 V., A.C.” (Code 
Rule 65c?) must be provided with fuse terminals. Although such 
a switch alone may be used for either voltage, there is no such inter¬ 
changeable rating for cutouts. See Tables 161, 164 and 166. That 
is, there is no approved cutout base which is suitable for both 250 volts, 
D.C., and 500 volts, A.C. 

Note.—Switches Rated At 300 Amp. Are To Be Used Only On 
Switchboards. The only standard cutout base (Nos. 5 and 11, 
Table 161) suitable for use with a switch of this size would be of the 201- 
400-amp. classification. This would enable the 300-amp. switch to be 
used with, say, a 400-amp. fuse which would not provide it with proper 


















































90 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 3 


protection. Therefore, at the time knife-switch ratings were standard¬ 
ized and made to correspond with the enclosed-fuse-cutout-base ratings 
(Table 161) the 300-amp. switch was retained as a special size for use 
only on switchboards. The 300-amp. switch was thus retained with the 
understanding on the part of the switch manufacturers that a 300-amp. 

switch would not be supplied by 




0 | 


1: •• p . "• ’• 


..* 


0 

S <1 A > 

5 



m 


Opposite Polarities Mounted 
-■ - ir~-- 

L 


Mm 


Switch 


0 



ft & 


’■■M- 




cx. 4) 

4*.i 


I s 

<o 


31* Section 
X-X 


them as a stock article for general 
use on individual bases. 

124. Minimum Allowable 
Spacings Between Parts Of 
Opposite Polarity which are 
outside the area bounded by 
the switch mechanism (Code 
Rule 65c) are given in Table 
125. This table of dimensions 
applies to busbars and enclosed 
fuses of either the cartridge or 
Edison-plug type, but it does 
not apply to open link fuses 
(Sec. 153). In panel-board 
construction, the busbars are 
mounted on either the same 
surface (S, Fig. 129), or one 
busbar is mounted over an¬ 
other ( B , Fig. 129) clear of the 
surface. Distance given in 
Columns 2 and 3, Table 125, are illustrated by A and B, 
Fig. 129. 


I-Front Elevation 

Fig. 129.—Part of panel-board showing 
parts of opposite polarity outside of the 
area bounded by the switch mechanism 
“mounted on same surface” and “mounted 
clear of surface.” 


125. Table Showing Minimum Allowable Distances Be¬ 
tween Parts Of Opposite Polarity Which Are Outside Of The 
Area Bounded By The Switch Mechanism. (Code Rule 65c.) 


Voltage 

{A, Fig. 129) When 
mounted on same 
surface, in. 

(B, Fig. 129) 
When clear of sur¬ 
face, in. 

Not over 125 V. 

H 

1H 

2 

X 

X 

m 

Not over 250 V. 

Not over 600 V. 





















































































Sec. 126] 


UNDERWRITERS’ REQUIREMENTS 


91 


.iSl 


..■■■Hinge-Jaw ^.-■break-jaw 


2 ), 


T 


y 


Contact- 
blocks . 



126. The Contact-block Which Carries The Break- And 
Hinge-jaws must be (Code Rule 65 b) secured to the base or 
mounting surface in such a manner as to prevent possible 
turning of the jaws. Manu¬ 
facturers usually meet this re¬ 
quirement by using dowel-pins, 
or screws as shown in Fig. 130. 

127. The Cross-bar Must Be 
Secured To Each Blade in such 
a manner as to prevent turning 
and twisting. This is usually 
accomplished by screws, dowel- 
pins, or a shoulder on the blade which fits snugly into a 
recess in the cross-bar. 


back- 

Connection 



'Screws To Prevent 
Turning Of Jaws 


Fig. 130. —Showing method of prevent¬ 
ing knife-switch jaws from turning. 


Note.—In Operating A Knife Switch, Firm Contact Must Be 
Quickly Made Between The Blades And The Jaws or severe arcing 
will result. This is not only injurious to the switch but greatly increases 
the fire hazard. Thus, if the jaws become turned, or if the union between 
the cross-bar and blades becomes loose, a heavy arc may be drawn when 
an attempt is made to close the switch. 

128. Switches Which Are Rated Above 400 Amp. At 600 
Volts, Or 600 Amp. At 250 Volts exceed the capacity of approved 

cartridge enclosed fuses (Table 
164). Such switches may be 
fused by arranging the fuses in 
multiple (Code Rule 65 d) pro¬ 
vided that: (1) As few fuses as 
possible are used. (2) The fuses 
are of equal capacity. (3) The 
multiple-arranged terminals for 
each pole are mounted in common 
as shown in Fig. 131. 

Example. —If it is desired to arrange 
multiple-fuse terminals for a two-pole 
knife switch which is rated at 800 
amp., 250 volts, two 400 -amp., 250 -volt 
fuses would be required for each pole (see 
Fig. 535). Although four 200-amp. fuses, or one 600-amp. fuse and one 
200-amp. fuse in each pole, would have ample capacity for the switch, 
neither of these latter combinations would comply with Code Rule 65 d. 



Fig. 131. —Fuse terminals mounted 
in common. 















































92 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 3 


129. A Switch Barrier (R, Fig. 132) is a block of insulating 
material which is placed between knife-switch jaws of opposite 
polarity. Barriers which are to be placed between the hinge- 
jaws (Fig. 132-7) must (Code Rule 65/) be of non-absorptive 
insulating material, and those which are to be placed between 
the break-jaws (Fig. 132-777) must be of a non-combustible, 
non-absorptive insulating material. The usual construction 
consists of a block or plate of non-combustible, non-absorptive 
insulating material extending from a point, Pi, outside of the 
area bounded by and between the break-jaws to a point, P 2 , 
similarly located with reference to the hinge-jaws as shown in 
Fig. 132-77. 




Hinae-Jaw .: -Barrier 


.-Break-Jaw 


Barrier... ^ 


I-Hinge-Jaws I-Top View TKr Break-Jaws 

Fig. 132.—Barrier used to decrease space normally occupied by switch. 


130. Barriers Are Used To Decrease The Base-areas 
Required For Switches. That is, if a properly-designed 
barrier is mounted on a switch, then the switch blades of 
opposite polarity may be set closer together than if a barrier 
is not used. Barriers that are designed to be placed between 
hinge-jaws must (Code Rule 65/) be of such a size and so 
located as to provide a separation between contact parts of 
opposite polarity (as measured along the shortest insulating- 
surface path over or around the barrier) which is equal to that 
required (Table 123) for switches without barriers. Further¬ 
more, the barriers must be so located as to provide a separation 
between other current-carrying parts equal to that specified 
in Table 125. Barriers that are designed to be placed between 
the break-jaws (Fig. 132-777) must (Code Rule 65/) be of 
such a size and so located as to provide a separation between 
contact parts of opposite polarity (as measured in the shortest 
path through air, over or around the barrier) which is equal 
to that required (Table 123) for switches Without barriers, 


































Sec. 131] 


UNDERWRITERS’ REQUIREMENTS 


93 


Explanation. — When Barriers Are Used On Switches between the 
hinge-jaws, it is, since no arc is produced at this point on opening and 
closing the switch, only necessary to provide sufficient insulation between 
the jaws to prevent “creeping” along the surface of the switch-base and 
barrier. That is, the distance, 2 A + 2B + C (Fig. 132), must at least, 
be equal to that given in Column 4, Table 123. 

When a current is suddenly broken, a back- or counter-electromotive 
force of self-induction is thereby produced. The voltage of this counter- 
e.m.f. is generally much greater than the normal voltage of the circuit. 
Thus, when a knife switch is operated to open a circuit, the voltage 
between the break-jaws of opposite polarity may be many times the 
voltage-rating of the switch. This high voltage will, if the dielectric 
(air path) between the break-jaws is broken down, cause a vicious arc 
to be established between the jaws. This arc, if once formed, may 
continue until the switch is entirely isolated from the source of voltage. 
Therefore, the path which has the lowest dielectric strength (the shortest 
air path, as 2D + E, Fig. 132) must at least be equal to the distance 
given in Column 4, Table 123. 

131. Sufficient Spacing For Multi-pole, Double-throw, 
Front-connected Knife Switches May Be Obtained By The 



• </ 


Barrier -"^—*- 


W 


A v- 





K-lii 


O 


• Front- 

'■V- T ; *.:•.Connection Lugs: 


tj.■■ 




o 

r-y-y ■ T"— "^“1 



=3 


o 

77-7 : •••. 


Insulating Base 

Fig. 133.—Showing method of obtaining required space between live metal parts of a 
multi-pole front-connected switch according to Code rule 65 g. 

Use Of Barriers, as shown in Fig. 133. In switches of this 
type front connection-lugs, L, are necessary on the inside jaws. 
Since these lugs extend out from the jaw, they reduce the 
horizontal clearance between jaws. The Code, Rule 6 5</, 
specifies that such switches must have standard switch spac- 
ings (Table 123) between live metal parts, or such spacing 
must be obtained by the use of barriers, as explained for 
hinge-jaw barriers in Sec. 130. That is, if the barrier is of a 














































94 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 3 


s-{5erv/ce Wires 


height, H, then (Fig. 133), the distance, A + 2H + W + B, 
must at least be equal to the distance specified in Column 4, 
Table 123. 

132. Auxiliary Contacts Of A Renewable Or Quick-break 
Type Must Be Provided On All 600-volt Knife Switches 
Which Have A Current-rating 
Of 200 Amp. Or Above, (Fig. 

134, and Code, Rule 65c). The 
Code does not require, but it 
does recommend that a switch 
of this type be used for break¬ 
ing direct-current circuits of 
over 250 volts. 

Explanation. —As the switch blade 
( B , Fig. 134) is opened, the auxil- 


£n 


J 


© 



T Spring 




33 



A 'Auxiliary Contact 

Fig. 134.—Quick-break switch required for Fig. 135.—Typical three-wire base- 
ratings greater than 600-v., 200-amp. ment service-entrance showing fuses in 

ungrounded wires. (Distribution panel 
is in basement in this installation.) 


iary blade, A, is at first retained by friction between the break-jaws, J. 
Meanwhile, as B is moved upward, the tension of the spring, S, 
is increased. Finally, as B is opened still further, the tension of S 
becomes sufficient that it overcomes the friction between A and the break- 
jaws. Then A is abruptly pulled or “snapped” from the jaws by S. 
This quick-break tends to prevent arcing because, under normal condi¬ 
tions, the arc does not, probably, have time to form. Thus, the auxiliary 
quick-break attachment renders it impossible to draw a dangerous arc by 
opening the switch slowly if the switch is used on a circuit within its 
rating. 

133. Switches Must Be Placed On All Service Wires (Code 
Rule 24a), whether overhead or underground, in the nearest 
readily-accessible place to the point where the service wires 
(Fig. 135) enter the building. Such a switch is called a service 
switch. 


Note.—Yard-wires Running From Building To Building In 
Private Plants are not considered as services (see Sec. 10). Switches 


























































Sec. 1341 UNDERWRITERS’ REQUIREMENTS 95 

aie not, therefore, required at the point where the conductors enter the 
buildings (Code Rule 24a), provided other switches are located on the 
mains or if the generators are nearby. 

134. The Connections To The Service Switch Must Ordi¬ 
narily Be So Arranged That When It Is Open The Current 
Will Be Cut Off From All Circuits And Devices Within The 
Building (Fig. 136). An exception is; that when the service 
switch, the service fuses, and the meter, are combined in an 
approved device, or a combination of such approved devices 
(Figs. 137, 138, and 139) which have no exposed wiring or live 
parts, then the switch may be so arranged that it does not 


.,-To Distribution Center 



Fig. 136. —Service switch so wired that all circuits and devices within the building 
may be disconnected by opening the switch. (Most watt-hour meters are designed to 
feed “from left to right,” which means that the wires from the source of voltage enter 
the left-hand side of the meter and leave at the right. The meter above illustrated 
feeds from “right to left.” In cities where ‘left-to-right” feed meters are used, the 
local inspection departments ordinarily require that the energy-supply wiring to the 
meter approach the meter from the left.) 


disconnect the fuses or the meter from the line. The approved 
device is a metal enclosure, constructed and proportioned in 
accordance with Under writers’ requirements, which encloses 
all live parts. 

135. Service Switches Must Be Enclosed In Metal Boxes 

(Code Rule 24a). except when used in connection with such 
approved devices as are specified in Sec. 134, or except when 
mounted on switchboards. The service switch is frequently 
installed (Fig. 137) on the panel-board within a service cabinet. 
































































































96 LIGHTING CIRCUITS AND SWITCHES [Div. 3 

This method of installation is not in accordance with the Code 
recommendation (not a requirement) that the service switch 



-imT " 0 

—— 

k* 



- - - Service 



Entrance 




/S\ —-1 


[[®QQ(d) 


<2 


y 


<--- 

-Meter 











Panel- 
Box , 

— With^ 

Door 

Removec 

/ 

j ✓ 

* 

* 

L 

f- 



-Service. 

Switch 


..Service 

Fuses 






~1 

'- 




v- 

0 

-Mif” 

- 

0 






Fig. 137. 


Fig. 138. 


Fig. 137.—Combination of approved devices wherein service switch may be so wired 
that meter and service fuses are not disconnected by opening service switch. Note that 
the National Electrical Code specifies that all service conduits must be permanently 
grounded unless insulated from the ground. Since the above service conduit is carried 
on a brick wall, it can scarcely be considered as being insulated. It should therefore, 
probably, be grounded. 

Fig. 138.—Compact combination of “approved devices.” (Trumbull Electric Mfg. 
Co. Service switch and fuses are in the cut-out box under the seal of the lighting com¬ 
pany, switch is externally operated by means of handle, H.) 


be of a type (Fig. 140) which may be operated without exposing 
the operator to accidental contact with any live parts. 
















































































































































































































































Sec. 135] 


UNDER WRITERS’ REQ UI REM ENTS 


97 



Fig. 139. Fig. 140. 

Fig. 139 .—Trumbull Electric Company meter service switch and box door open. 
Fig. 140.—Enclosed externally-operated service switch. (The words On and 
“Off” are stamped in proper positions in the side of the sheet metal box opposite the 
extreme positions of the operating handle.) 



Fig. 141.— An indicating surface switch. (When the switch is open, off is visible 
through the slot. When closed, “ on” is visible. All exposed parts of the switch shown 
are of porcelain.) 


7 














































































































































































































98 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 3 


136. Service Switches Must Plainly Indicate Whether 
They Are Open Or Closed (Code Rule 24a). If the switch 
is of the knife-switch type (Fig. 137) not externally operated, 
no further provision for indication is necessary; the position 
of the switch blades shows whether it is open or closed. 
However, if the switch is of the externally-operated type (Fig. 
140), or of the “snap” type (Fig. 141), the words “on” and 
“off” must be shown and be so located as to plainly indicate 
whether the switch is open or closed. 

137. Service Switches Must Disconnect All Ungrounded 
Wires Of The Circuit (Code Rule 24a). A disconnecting- 
strap may be employed in lieu of a switch blade for grounded 

conductors. With three-wire, 
single-phase, alternating-current 
systems, which have a grounded 
neutral, or three-wire direct- 
current systems, the service 
switch may be so designed (Fig. 
142) as to permit either outside 
wire to be opened, independently 
of the other, but the design must 
be such that the neutral cannot 
be opened without opening both 
out side wires (see Sec. 206). 

138. Switches Must Always 
Be Placed In Accessible Places 
And Must Always Be Grouped 
Insofar As Possible (Code Rule 
24b). In the event of a short 
circuit causing a fire, the faulty circuit may be more quickly 
disconnected if all switches are located in one group than if they 
are scattered throughout a building. Furthermore, concentrat¬ 
ing the switches at a certain location facilitates rapid testing. 

Note.—Service Switches Should Not Be Placed Behind Obstruc¬ 
tions such as shelving, cabinets, or the like. They should also be 
mounted at a height of not more than about ft. from the floor. 

139. Switches Must Be Installed, When Possible, In Dry 
Places (Code Rule 24 b). However, if it is necessary that 
they be placed in damp places such as basements and similar 


.■Neutral 



Ipi-pl 


Copper . ’ 
Strap In 
Neutral: 


^Service 
■ Fuses 


mm 
II; 


Base : 


Fig. 142. — Service switches on 
three-wire grounded-neutral system 
so arranged that neutral cannot be 
opened without opening both outside 
wires. 


















































Sec. 140] 


UNDERWRITERS’ REQUIREMENTS 


99 



locations, they must (Code Rule 19c) be mounted in approved 
boxes or cabinets. When located in wet places, or outside 
of buildings, they must be 
mounted in approved weather¬ 
proof boxes or cabinets. The 
metal parts of a switch which 
is located in a damp place will 
usually corrode. The current- 
carrying parts may thereby be 
so affected that the switch will 
not function properly in closing 
the circuit. Or it may corrode 
so badly that it cannot be 
opened readily. Switches in¬ 
stalled in damp places are also 
more susceptible to internal short-circuits than when installed 
in a dry place. 

140. Knife Switches Should Be So Wired (Code Rule 246) 
that: (1) The blades will, when possible, be dead (Fig. 143-77) 
when the switch is open. 

(2) Gravity will not tend to 
close them. Accidental con¬ 
tact or short circuit which 
might be produced by the 
human body or by a screw¬ 
driver is not so likely to 


I-Incorrect TL* Correct 

Fig. 143. —Correct and incorrect 
method of wiring a single-throw knife 
switch. 


Catch To Hold 
Blades In Open 
' Position 




[[ 

n 

h 

"W 



i 




-i-iu 


I 



Fig. 144. — Double-throw switch 
so mounted that the throw is hori¬ 
zontal. 


Fig. 145. —Double-throw switch, so mounted 
that throw is vertical. (It is provided with 
catch, C, which engages in a depression in B, 
to hold blades in open position. This pre¬ 
vents the blades being closed by gravity.) 


occur if the blades are dead (Fig. 143 -II) and the break-jaws 
alive, as if the blades are alive (Fig. 143-7) and the break-jaws 





























































































100 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 3 


dead. The Code requires that all single-throw knife switches 
be mounted so that gravity will not (Fig. 143) tend to close 
them. A double-throw knife switch may be mounted so that 
the throw will be horizontal (Fig. 144), or vertical, but if the 
throw is vertical a locking device (Fig. 145), which is so con¬ 
structed as to securely hold the blades in the open position 
when they are so set must be provided. 

141. Single-pole Switches Must Not Be Used As Service 
Switches (Code Rule 24c). A single-pole switch, when 
open, does not effect complete isolation of the circuit which it 
controls. If, in a two-wire ungrounded lighting system, a 
single-pole switch (Fig. 146) was used as a service switch, 


A 



Branch < 


...Single-Pole 
Service Switch 


VB 


'.-Lamps-' 

r X 


Service 

Wires 


This Wire Cannot Be Isolated From f- 

Circuit By Service Switch -— 


Fig. 146.—Single-pole switch should not be used as a service switch. 


there would be no direct means of disconnecting wire B from 
the source of voltage. Consequently a workman might, while 
making repairs to the line, be severely injured. Also, if B 
came in contact with a water-pipe, or otherwise became 
grounded, sufficient current might flow to eventually cause 
a fire, and yet not rupture the fuse. The current-flow could 
not, in this case, be stopped by opening the single-pole service 
switch, S. 

Note.—Single-pole Switches Should Not Be Used To Control 
Circuits Which Are Located In Damp Places (Code Rule 24c). 
A circuit which is located outside of a building or in a damp place is more 
likely to become grounded than is one which is otherwise located. There¬ 
fore, the controlling-switch for such a circuit should provide a means of 
complete isolation of the entire circuit. The average basement is not 
usually considered a damp place and therefore would not ordinarily 
require a double-pole switch. Rooms in which much washing is done, 
rooms in which there is steam, dye rooms and sometimes garages may be 
considered as damp places. When in doubt, consult the Electrical 
Inspection Department which has jurisdiction. 

























Sec. 142] UNDERWRITERS’ REQUIREMENTS 101 

142. Single-pole Switches Must Never Be Placed In The 
Neutral Wire Of A Three-wire System (Code Rule 24c) 
except in a two-wire branch (Fig. 147) or tap circuit supplying 
not more than 660 watts. (See Sec. 171 for results of open 
neutral.) The neutral wire of practically all three-wire 


+. ■ -teufra! Wire,In Which Single-Pole Switch Cannot Be Placed 
z'* 

/ Single -Pole Switch 

CH 



Lamp - 


Branch Circuit 

1 Supplying Not 

More Than 600 Watts 

A W-*" Permanent Ground ~W 


B 


.-■■Accidental 
Grounds - 


-r-:: 

~ < - 


-<- 




Fig. 147.—Undesirable arrangement showing conditions which may occur when a 
single-pole switch is installed in that side of the branch circuit which is connected to 
the neutral of a three-wire system. 


lighting systems is permanently grounded, usually outside 
the building. Therefore, if the switch is placed in that side 
of the branch which connects to the neutral, as shown in Fig. 
147, and an accidental ground should occur, as at C, the cur¬ 
rent will flow through D, L, C, and along the path through the 



Fig. 148. —Preferable arrangement. Single-pole switch, when connected into that 
side of the branch which connects to the outer wire of a three-wire system, can be used 
to isolate an accidental ground. 


ground as shown by the dotted arrows, to A, thus rendering it 
impossible to extinguish the lights by opening the switch, S. 
If the other side of the branch should accidentally become 
grounded as at B, a short-circuit current, which may be 
extremely dangerous and difficult to locate, will flow through 
DBA. If, however, (Fig. 148) the single-pole switch is 




































102 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 3 


installed in that side of the branch which connects to the 
outer wire, neither of the conditions illustrated in Fig. 147 can 
occur. 


Note.—The Reason Why Double-pole Switches Are Usually 
Provided On The Branch Circuits In Panel-boxes And At Dis¬ 
tribution Centers is not on account of any Code rule, but because the 
double-pole switch, when open, completely isolates the branch circuit 
from the mains. Although a single-pole switch installed in the “hot” 
wire (Fig. 148) of a two-wire branch from a three-wire-grounded-neutral 
system, will, when open, render the circuit “dead,” most manufacturers 
prefer to equip their panel boards with double-pole switches in the branch 
circuits for the following rea’sons: (1) There are many systems wherein the 
neutral is not grounded , and the manufacturer may not know beforehand 
for what kind of a system the panel board will be used. Therefore , panel 
boards are practically always supplied with double-pole switches in the 
branch circuits so that they may be adapted to any system. (2) Equipping 
all panel boards with the same type of switch minimizes the number of 
switches and parts which must be carried in stock. There are however 
a number of installations with single-pole switches in the branch circuits, 
a number of which may be found in New York City, which were engi¬ 
neered by J. Bassett Jones. 


-q 

^ _ 


Service Switch 
Service Cabinet 
I-4-" Meter 


"Porcelain 

Bushing 


-azD- 

-4LZD- 


Location Of 

Single-Pole 

Switch 

J Fuse 


•o 


Distribution A 

Centers- c' 


Main, - 
(Capacity 
7640Watts) 


N 


$ 


143. Single-pole Switches Are Not Generally Used On Any 
Circuits Supplying More Than 660 Watts. Although the use 

of single-pole switches is not 
specifically prohibited by the 
Code, except as outlined in 
Sec. 142, and practical con¬ 
siderations usually render it 
unwise to employ single-pole 
switches for controlling cir¬ 
cuits, the wattage of which 
exceeds 660. Many wiring 
inspectors will not permit the 
use of single-pole switches for 
controlling circuits of capaci¬ 
ties exceeding 660 watts. The 
double-pole switch always has 
the advantage that, when 
opened, it cuts both legs of the controlled circuit “dead.” It 
thereby minimizes the possibility of difficulty due to shock 
by accidental contact or by fire. 


Branch Circuits 
EachSuppiying 
660 Watts-.. 


660Watts {l 






\ *• 





X 












:X 

P 




Edison Plug Cutouts— 

Fig. 149.—Showing how a single-pole 
switch might be installed at X for the con¬ 
trol of a circuit MN of a wattage exceeding 
660. 













































Sec. 144] 


UNDERWRITERS’ REQUIREMENTS 


103 


Example. —There is nothing in the Code to prohibit the installation 
of a single-pole switch, of proper capacity, at X in Fig. 149. A switch 
thus placed at X would, when opened, “turn off” all the lights feeding 
from panel P. But it might not, when open, render “dead” both sides 
of the circuit beyond it. Hence, the use of single-pole switches for 
applications such as that of Fig. 149 should be discouraged. 

144. Three-way Switches Are Considered As Single-pole 
Switches (Code Rule 24c). Four-way switches, and those 
types of electrolier and series-parallel switches which do not 
disconnect both wires from the source of supply, are also 
considered as single-pole switches, and the rules of Secs. 141, 
and 142 relating to single-pole switches likewise apply to these 
types just mentioned (see Sec. 251). 

145. Flush Switches Or Receptacles Must Always Be 
Enclosed In An Approved Iron Or Steel Box, except as noted 
below. This metal box (Fig. 150) must be used in addition 


Supporting-Flange For Securing Box To 



Fig. 150.—Metallic flush switch-box for a two-gang installation. 

to the porcelain enclosure which forms a part of the switch or 
receptacle. This rule is intended to protect the switch against 
mechanical injury and to minimize the possibility of a fire 
being started inside the wall, in which the switch is installed, 
due to injury to the switch, or to arcing in the switch. 

Note.—Receptacles And Attachment Plugs At Floor Outlets 
Must Be Enclosed In Floor-outlet Boxes (Code Rule 24 d) which 
have been especially designed and approved (Fig. 151) for this purpose. 









































































































































104 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 3 


However, where such devices are so located that they are not subject 
to mechanical injury or dampness, departure from this rule may be 
allowed, but permission for such departure must be obtained in writing 
from the inspection bureau having jurisdiction. 




Permanent ; 
Cover 


■RoundRubber Gasket Fibre .. 

Flat Rubber Gasket .-Flat Brass Plug ‘Bushing 


; F/anged Cast-Iron Ring 
Reversible Cover 


1-Showing Position Of Reversible 
Cover When Box Is Not In Use 


I-Showing Position Of Reversible 
Cover When Box Is Being Used 
As An Outlet 


Fig. 151.—An approved adjustable floor outlet box. ( Frank Adam Electric Co. 


146. Flush-switch Boxes Must, When Possible, Be Sup¬ 
ported By %-in. Blocks (Figs. 152 and 153). The blocks must, 
in new-building work, be fastened between the studs, flush 
with the back of the lath (Code Rule 24e). The switch-box 
is then usually adjusted on the supporting flanges (Fig. 150) 
so that the front of the box (Fig. 152-77) will project outward 



about in. from the face of the studding, thus making the 
front edge of the box approximately % in. from the outer 
surface of the laths. Since the plaster is usually about % in. 
thick (measured from the face of the studding) the front of the 
switch-box will then lack about in. (Fig. 153) of being flush 
with the outer surface of the plaster. This permits the switch¬ 
supporting screws to be left in the box while the plastering is 










































































Sjr. 146] 


U N DERWRITERS ’ 7? EIRE MEN TE 


105 


Stud ■...•> 

Lathe-. 

Plaster- -. p 



..^.. 

Afsproxlmatelu . 



?/7?a/ Z 




.. / ; 

S’ 


.-Screw Which Secures 
Switch Box To Lath 


2 "x 4-"S+ud 


..-Flange On Box Set 
’ B Flush With Outer 
Surface Of Piaster 


Switch Box 


Fig. 153. Fig. 154. 

Fig. 153.—Installation of flush switch in new building. 

Fig. 154.—Installation of flush switch box in plastered partition wall of finished 
building. (All of lath B, and approximately one half of each of iaths A and C are cut 
away to admit box. This leaves about one half of each of laths A and C, to which the 
box is secured by screws.) 



Fig. 155.—Flush switch-box installed on surface base block in a finished building. 





























































































































































10G 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 3 


being done. Thereby, their tapped holes are prevented from 
filling with plaster. 



Fig. 156.—Installation of steel outlet box for baseboard outlet. 



Fig. 157.—Metal box installed for baseboard outlet. 

When cleats back of the lath cannot be provided, as in 
wiring a finished building, the switch-box may be held to the 



















































































Sec. 147 ] 


UNDERWRITERS ’ REQUIREMENTS 


107 


lath (Fig. 154) by screws through the supporting flanges. 
There is a question as to whether the construction of Fig. 154 
is in strict conformance with Code Rule 24e; but it is a fact 
that most wiring inspectors will approve this construction 
for finished-building wiring. Or if adequate support cannot 
be thus provided, it may be fastened to wooden base-blocks 
(Fig. 155) of not less than A in. in thickness, mounted on the 
face of the wall, which must in turn be securely fastened to 
the lathing with screws. A typical baseboard-outlet installa¬ 
tion is illustrated in Figs. 156 and 157. 

147. Snap Switches Are Recommended For The Control Of 
Lighting Circuits which do not carry more than 30 amp. or 
which do not have a voltage exceeding 250 volts. They 
should preferably be of the indicating type. Snap-switches 
are, since the contact-bars and jaws are enclosed, usually 
safer from the standpoints of both life and fire hazard than 
are the ordinary types of knife switches. 

148. Snap Switches, When Used In Knob And Cleat Work, 
Must Be Supported By Sub-bases (Code Rule 24/) of 





<— 


I-Plan 


2 Minimum---'' K'->i 


Wire Slots 


Screw Slots 


E-Sect ion A-A 


Fig. 158. —Snap switch mounted on por- Fig. 159. Porcelain sub-base foi 
celain knobs in knob and cleat work. mounting snap switch in exposed knob 

. and cleat work. 


non-combustible, non-absorptive insulating material, the 
sub-base must be so designed that the wires will be sepa¬ 
rated (Figs. 158 and 159) from the surface wired over by 
a distance of at least l A in. This is intended to prevent the 
wires from touching the surface which supports the knobs or 

cleats. 




























108 LIGHTING CIRCUITS AND SWITCHES [Div. 3 

149. Snap-switch Sub-bases Must Be Used In Raceway 
Work, except that when the switch is so constructed that it is 
approved for mounting directly on the moulding, the sub-base 
may be omitted (Code Rule 24/). Raceway-work sub-bases 
are frequently made of porcelain (Figs. 160 and 161) although 
they may be of hard wood. 




Fig. 161.—Porcelain sub-base for snap 
switch in metal-raceway work. 


Snap- 
Switch . 

Conductors 


Meta! Raceway, 


Porcelain 

base 


Fig. 160.—Snap switch mounted on por¬ 
celain base for metal-raceway work. 


150. A Switch Must Be Used To Control Each Heating 
Appliance (Code Rule 25a, 2) or each group of heating appli¬ 
ances which have a capacity of more than 6 amp. or 660 watts. 
This switch must: (1) Plainly indicate whether current is “on” 
or “off.” (2) Be within sight of the heating appliance and 
readily accessible in case of emergency. (3) Disconnect all 
wires of the circuit. This necessitates the use of a multi-pole 
switch. The single-pole switches on the individual units of an 
electric range are not to be considered as taking the place of 
the switch which is specified above. 

Note.—An Approved Attachment Plug May Be Used Instead Of 
The Switch Mentioned Above provided the rating of such a plug does 
not exceed 30 amp. 

Note.—Portable Heating Appliances Must Have Plug Con¬ 
nectors (Code Rule 256, 2), so arranged that the plug may be pulled out 
to open the circuit. The plug must be so designed that no live parts 
are exposed, either when it is connected to the appliance or when dis¬ 
connected therefrom. The connector may be located at either end of the 
flexible conductor, or inserted in the conductor itself. 

151. Fuses May Be Classified as: (1) Open link, (Fig. 162). 

(2) Enclosed, (Fig. 163). Enclosed fuses may be further 
classified as: (a) Edison-plug type, (FiG. 163-/). ( b ) Ferrule- 

contact type (Fig. 163 -II). (c) Knife-blade-contact type, (Fig. 












































Sec. 152] 


UNDERWRITERS’ REQUIREMENTS 


109 


163-7/7), The knife-blade and ferrule type fuses are also 
sometimes called cartridge fuses. The more-frequently- 



Fig. 162.—Open-link fuses for cutouts, switches, and panel-boards. 


encountered requirements of the Code which relate to fuse 
installation are treated in the following sections. 



Ferrule Terminal--. 


Knife-Blade Terminal- . 











1,. ~ ; ■*—• 






Standard Edison-Plug 
''-'Screw Thread 


7 ~ 

TubeCap---' 


™° n H-Ferrule Contact TH-Knife-Bl a d e 
Plug Contact 


Fig. 163.—Various types of approved enclosed-fuses. 


152. Link Fuses, when ruptured by an overload current, 
produce a heavy arc and throw molten metal about. Hence, 
unless properly mounted and enclosed (Sec. 158), they provide 
a dangerous fire hazard. Because of their low cost, they are 
well adapted for, and give good results in certain industrial 
plants where they are under expert supervision. They should 
not, however, be installed in residences, office buildings, or in 
any location where they may be 
handled by uninformed persons. 


Slate Or Marble Base-,, 


Note.—The Code Does Not Per¬ 
mit The Use Of Link Fuses which 
have a capacity exceeding 1,000 amp. 
nor which operate at a pressure in 
excess of 250 volts. 


p- B 


r 

-'/ Lugs ■ ' A ■ ; ( f^Tips'. 



''fuse Bloch Terminal 


Fig. 164.—Two-pole open-link fuse 
cutout. (See Table 154 for significance 


153. The Spacings Of Open 
Link Fuses must not be less 

than those given in Table 154 of reference lettcrs A and B , 

(Code Rule 67a). The dis¬ 
tances, as given, apply only to plain open fuse-blocks, mounted 
on slate or marble bases, and are to be measured between the 
nearest metal parts (Fig. 164), exclusive of the fuse wire 






















































































































110 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 3 


proper. That is, if the copper fuse-tips, T, overhang the 
edges of the fuse-block terminals, F, the spacing is measured 
between the nearest edges of the tips. 

154. Table Of Spacing Distance For Link Fuse Cutout 
Bases. (Code Rule 67a.) 


Ampere capacity 

Minimum separation 
of nearest metal 
parts of opposite polar¬ 
ity, A, Fig. 164, 
inches 

Minimum break dis¬ 
tance, B, Fig. 164, 
inches 

Not over 125 volts 

0-10 

% 

% 

11-100 

1 

H • 

101-300 

1 

l 

301-1,000 

IK 

IK 

Not over 250 volts 

0-10 

i X 

IK 

11-100 

m 

i K 

101-300 

2 

l K 

301-1,000 

2K 

2 


Note.—The Required Spacing Between Open Link Fuse Termi¬ 
nals Of The Same Polarity (Code Rule 67a) is at least K in. for 
voltages up to and including 125 volts, and at least K in. for 
voltages between 126 and 250 volts. This is the minimum distance 
allowable. Greater separation than that given above should be provided 
when it is practicable to do so. These spacings are intended to prevent 
the melting of a link fuse by the blowing of an adjacent fuse of opposite 
polarity. 

155. The Spacing For Open-link Cutout Bases When Used 
In Three-wire Systems must (Code Rule 67a) be at least 
equal to the distance as given in Table 154 for circuits of the 
potential of the outside wires, except that the cutouts in a 
125-volt two-wire branch (Sec. 171) of a 125-250-volt- 
grounded-neutral system may have the spacings as specified 
for not over 125 volts. 

156. Bases For Link-fuse Cutouts must conform to the 
requirements as given in Sec. 121 for switch bases, except that 































Sec. 157] 


UNDERWRITERS’ REQUIREMENTS 


111 


the holes lor the supporting screws must be kept outside of the 
area bounded by the outside edges of the fuse-block terminals. 
That is, a screw located at S, Fig. 126, would not be permitted 
in a link-fuse cutout base. 

167. Link Fuses Must Be Stamped (Code Rule 686) with a 
number indicating 80 per cent, of the maximum current, in 
amperes, which they can carry indefinitely. This allows 
about 25 per cent, overload before the fuse will melt. Thus, 
a link fuse which is rated at 80 amp., must, to comply with 
the Code requirements, carry indefinitely a current of 100 amp. 
without rupturing. 


Note.—The Contact Terminals Of Link Fuses must be of copper or 
aluminum, (Code Rule 68a) and must have perfect electrical connection 
(soldered or welded) with the fusible part of the strip. 

158. Link Fuses May Be Used (Code Rule 23c) only on 
switchboards, or when mounted on approved bases which 
must be installed (Fig. 165) 
in approved cutout boxes or 
cabinets. When they are 
mounted on switchboards, 
the cabinet and the cutout 
base are not required. When 
installed in approved cutout 
boxes or cabinets, a space of 
at least 2 in. (Fig. 165) must 
be provided between all points 
on the open link fuse (either 
the fuse-wire proper or ter¬ 
minals thereof) and any part of the cabinet, such as the metal 
walls, metal-lined walls, doors, or the glass-paneled doors. 

159. The Fuse Terminals Of An Enclosed-fuse Cutout 
Base must, except for sealable service and meter cutouts, 
(Code Rule 676) be of either the Edison-plug (Fig. 166-7), 
spring-clip (Fig. 166-77), or knife-blade type (Fig. 166-777), to 
take the corresponding standard enclosed fuses. The spring- 
clip and knife-blade type of fuse terminals must be secured to 
the base by two screws (Fig. 166) or the equivalent thereof, 
so as to prevent them from turning. End stops must be 
provided for the cartridge-type fuse terminals to insure proper 



Sheet-Meta I Box- 

Fig. 165.—Two-wire cutout box with link 
fuses. 


























112 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 3 


location of the fuse in the cut-out base. This is, in the knife- 
blade fuse, provided by the cap, (C, Fig. 163) which fits against 
the jaws of the terminal, and in the ferrule type, by a small 
lip of turned-over metal (E, Fig. 166-77), on each spring-clip, 
against which the ferrule-contact abuts. 





Edison Screw 
-Shell 


I" Edison Plug 
Terminal 


Porcelain 

Base 


'Bindinq 
Post 

ws 

Prevent 
Turning 

nirKmfe Blade 
Terminal 


Fig. 166.—Types of approved fuse-terminal receptacles for enclosed fuses. 


Note.—Sealable Service And Meter Cutouts are cutouts which 
are installed under the seal of a lighting company, and are therefore 
only accessible to and handled by experienced persons. The fuse 
terminals of such a cutout need not conform to the styles as mentioned 
above. Ah enclosed fuse having terminals which may be used for this 
class of service is illustrated in Fig. 167. It is obvious that when installed 
by a properly informed person, better contact may be provided by the 
correct adjustment of the holding-nuts, than may ordinarily be obtained 
by the use of the ferrule or knife-blade type of fuse. 


PI eta! Cap .. 


r — 



_: 

zLtz: 

It) 

L——O 

— 


=== 



. A —"— 

FI her Tube--' Terminal •' 

Fig. 167.—Type of enclosed fuse which may be used for service and meter cutouts when 
installed under seal of lighting company. 


160. Every Approved Enclosed-fuse Cutout Base Is Rated 
In Regard To Both Current And Voltage in accordance with 
some one of the 19 standard ratings shown in Table 161 (Code 
Rule 67c). The bases are so designed (see Table 166) that 
one of a certain rating cannot be used with fuses which have 
either a higher voltage—or a higher current-rating. 

Example. —A cutout base which is rated at 31-60 amp., 250 volts, 
must be so constructed that it is impossible to fuse it with a 65-amp., 
250-volt fuse, or with any 600-volt fuse, even though the ampere-rating 
of the 600-volt fuse is less than that of the cutout-base rating. 


















































Sec. 161J 


UNDER WRITERS ’ REQ VI REM ENTS 


113 


161. Table Showing Classification Of Cutout Bases For 
Enclosed Fuses. (Code Rule 67c.) See note below. 


Rating 

Not over 250 volts, 

Rating 

Not over 600 volts, 

number 

amperes 

number 

amperes 


Standard Plug or Cartridge Cutouts 


1 

0-30 

7 

0-30 

2 

31-60 

8 

31-60 

3 

61-100 

9 

61-100 

4 

101-200 

10 

101-200 

5 

201-400 

11 

201-400 

6 

401-600 




Sealable Service and Meter Cutouts 


12 

0-30 

16 

0-30 

13 

31-60 

17 

31-60 

14 

61-100 

18 

61-100 

15 

101-200 

19 

101-200 


Note. —The above Rating Numbers 1 to 19 inclusive have been 
assigned arbitrarily by the author and are not authorized by nor do 
the}' appear in the Code. Every approved enclosed-fuse cutout base 
conforms to one of the 19 above ratings. 

162. An Approved Enclosed Fuse Is Marked With: (1) 

The words “N.E. Code Std.” (2) The voltage and current 
rating. (On ferrule-contact fuses, this marking is on the 
ferrule or the tube, and on knife-blade-contact fuses, it is on 
the cap or the tube.) (3) A paper label (for cartridge fuses) 
which is green in color for 250-volt fuses, and red for 600-volt 
fuses. This paper label must bear the name or trademark of the 
manufacturer and the voltage for which the fuse is designed. 

163. The Style Or Type Of Terminals For Enclosed Fuses, 
Fig. 163, (except for sealable service and meter cutouts, Sec. 
159) must correspond to that specified in Table 164 (Code Rule 
68 /). 

164. Table Of Current And Voltage Classification For The 
Various Types Of Approved Enclosed Fuses And Fuse Termi¬ 
nals (except for sealable service and meter cutouts). See 

following notes. 

8 


































114 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 3 


Rating 

number 

Ampere 

rating 

Type of fuse and terminal 

Not over 250 volts 



A. Cartridge fuse (ferrule contact). 



B. Approved plugs, or cartridge fuses in 

1 

0-30 

approved casings for Edison plug cutouts, 
not exceeding 125 volts, but including any 
circuit of a three-wire 125-250-volt 
system with grounded neutral. 



Cartridge fuse (ferrule contact) for use 

2 

31-60 

also in approved casings for large size 
Edison plug type 250-volt cutouts. 

3 

61-100 


4 

5 

101-200 

201-400 

Cartridge fuse (knife blade contact). 

6 

401-600 


Not over 600 volts 

7 

8 

0-30 

31-60 

Cartridge fuse (ferrule contact). 

9 

61-100 


10 

101-200 

Cartridge fuse (knife blade contact). 

11 

201-400 



Note. —The “Rating Numbers” 1 to 11 inclusive were assigned by the 
author and do not appear in the Code. These correspond with the 
11 rating numbers given in Table 161 for “Standard Plug Or Cartridge 
Cut-outs.” A different-size approved Code standard cutout base is 
manufactured for each of these 11 ratings as shown in Table 165 and in 
addition Edison-plug-cutout bases are manufactured for ratings numbers 
1 and 2. 

Note.—The Above Classification Of Enclosed Fuses May Be 
Summarized As Follows: 

1. The maximum voltage is 600 volts. 

2. The maximum current-carrying capacity is 600 amp. at 250 volts, 
and 400 amp. at 600 volts. 

3. The maximum rating of the Edison-plug type is 60 amp. at 250 volts. 

4. The maximum rating of the ferrule-contact type is 60 amp. at 
600 volts. 

5. The minimum current rating of the knife-blade-contact type is 
61 amp. (actually 65 amp., since the smallest fuse regularly manufactured 
in this class is of 65-amp. capacity). 


















































165. Table Of Dimensions Of The National Electrical Code Standard Cartridge Enclosed Fuse. 


Sec. 165] UNDERWRITERS’ REQUIREMENTS 


115 




-h 

o 

c3 

-H 

o 

o 

0> 


*2 

3 

i 

OS 


'8 


0? 

co 

3 


0) 

hC 

3 

M 

q3 

o 


<N 

2 

h 

o 

pH 

I 

as 


6 

Ph 


o 

a 

-h 

a 

o 

o 


p 

M 

u 

o 


as 

CO 

a 


b€ 

T3 


c3 

o 


2 

u 

O 

pH 

I 

00 

co 


d 

HI 


Rated 

capacity, 

amperes 

0-30 

31-60 

61-100 

101-200 

201-400 

401-600 

0-30 

31-60 

61-100 

101-200 

201-400 


Width of 

terminal 

blades, 

inches 

• • 

V* \O0 N >P0 

C0\ H\ WS\ 

H H (M 

■ 

V# \Q0 \S© 

P5\ H\ »0\ 

rH pH 

fc, 

Dia. of 

tube, 

inches 

\(N 

<o\ 

H\ H\ 

rH rH 0} 


Vf \H \cq 

i—T\ CO\ h\ 

rH rH 

* 

Min. length 
of ferrules 
or of termi¬ 
nal blades 
outside of 
tube, 
inches 

\N \Q0 

\« \00 \H 

«0\ t»\ 

rH1 rH rH O'! 

\N \00 

i-N V5\ 

\00 \00 
«\ t-\ 

rH rH rH 

Q 

Diameter of 
ferrules or 
thickness 
of terminal 
blades, 
inches 

tO 

to \H 
\rH C0\ 
Ci\ H 

to 

\« \H 

i-i\ .'0\ n\ pH\ 

to 

\H CO 
«\ \H 

H rH\ 

rH 

to 

NP0 \H 

H\ C0\ r-f\ 

o 

Width 

of 

contact 

clips, 

inches 

\0* \00 
r-N »0\ 

\00 \H \00 

H\ C0\ rH\ 

rH rH 

\<N \00 
h\ W5\ 

\» V* V* 
t'-N h\ co\ 

rH tH 

cq 

Distance 

between 

contact 

clips, 

inches 

V* 

w\ 

rH ^H 

\N 

i—\ 

^ to O 

Mb 

f 

CO N 00 


Length 

over 

terminals, 

inches 

IN CO 

\00 \00 \p0 N00 

i-\ i-K m\ «\ 

if) N00 O 

rH 

lO 

\00 \Q0 \O0 
kO\ 

N OS H 
rH 

Form 

number 

Form 1 

Form 2 

Form 1 

Form 2 

Rated 

capacity, 

amperes 

0-30 

31-60 

61-100 

100-200 

201-400 

401-600 

0-30 

31-60 

61-100 

101-200 

201-400 

Rating 

number 

—i IN 

CO ic CO 

t> 00 

9 

10 

11 

Voltage 

Not over 
250 

Not over 
600 


Note. —The 11 Rating numbers have been assigned by the author and are not authorized by the Code. 















































































































































116 


LIGHTING CIRCUITS AND SWITCHES 


[Dry. 3 


166. The Dimensions Of Cartridge Enclosed Fuses, except 
for sealable service and meter cut-outs, must conform to those 
specified in Table 165. The reference letters in Table 165 
refer to Figs. 168 and 169. 

Note.—For Spacing Distance Between Parts Of Opposite 
Polarity Of Enclosed Fuses see Column 2, Table 125 (Code Rule 
696). Parts of enclosed fuses of the same polarity may be located as 
close together as convenience in handling will allow. 

167. Automatic Cutouts (Fuses Or Circuit Breakers) 
Must Be Placed In All Ungrounded Service Wires (Code, 
Rule 23a) in the nearest accessible place, as shown in Fig. 135, 
to the point where the service enters the building, and arranged 
to cut off the current from all circuits and devices within the 
building except the service switch (Sec. 134, Fig. 136). Under 
the conditions shown in Fig. 137, both meter and switch 
may be so connected that they will not be disconnected by the 
service cutout. This is to enable an uninformed person to 
disconnect (by the opening of the service switch) the fuses 
from the source of voltage when installing a new fuse, thus 
tending to decrease the probability of an accidental short 
circuit, and a possible consequent fire or personal injury. In 
the approved combination of compact devices (Sec. 134), the 
fuses are usually enclosed in a metal cabinet which is sealed 
by the lighting company, and it is therefore presumed that 
live parts are accessible only to experienced persons who will 
not establish accidental short circuits. Thus, the internal 
connections of such a device may be arranged in any desired 
manner that will facilitate the manufacturing or installation 
requirements. 

Note.—The Yard Wires Which Extend From Building To Build¬ 
ing In A Private Plant Are Not Considered As Service Wires, and 
need not be fused at the building-entrance provided that the next fuse 
back toward the source of energy is small enough to protect the wires 
inside the building in question according to Table 170. See Note under 
Sec. 133. 

168. Service Fuses Must Be Enclosed (Code Rule 23a) so 
that live parts are not exposed to accidental contact, except 
that when they are mounted on switchboards which are subject 


Sec. 169 ] 


UNDERWRITERS ’ REQUIREMENTS 


117 


to competent supervision they need not be enclosed. The 
term “enclosed,” in the sense herein implied, means contained 
in an approved non-combustible or sheet-metal box or cabinet 
(Figs. 137 and 140) and does not mean an “enclosed-fuse.” 

169. Fuses Must be Placed At Every Point Where A 
Change Is Made In The Wire-size, (Code Rule 236) unless 
the fuse (Fig. 170) in the larger wire will protect the smaller 
wire. Such a fuse must, for the given size of the wire which 
it is to protect, have a rated capacity which does not exceed 
that specified under the column headed Table A, B, or C, of 
Sec. 170, according to the insulation of the wire. 


-yNo. 4, B. & 5. Gage, Rubber-Covered Wire 


, , To \ » ; 

Mam • M 

n— n ’• ' ^ 

B 

c 

^..■■50-Amp. t 

Fuses L 

H 

pV -~ C5-Amp. Fuses 
\-;No. 8 B.&.5. Gage, 

F Rubber-Covered Wire 

. ." 

,.T 

<-No Fuse 
Reguired 
Here 


No. 6 B. & 8. Gage, Rubber Covered Wire-' ' 


Fig. 170. —Illustrating Code requirement for fusing wires at points where the wire- 
size changes. (Such an arrangement of wire sizes as shown herein would usually be 
uneconomical and undesirable. It is only shown for explanation purposes.) 


Example.—The Code Requirements For Fusing Wires At Points 
Where A Change Is Made In The Size Of The Wire is illustrated in 
Fig. 170. In this illustration, a No. 6, B. & S. gage, rubber-covered wire 
is connected to a No. 4 B. & S. gage, rubber-covered wire at C, and a 
No. 8, B. & S. gage, rubber-covered wire is connected to the No. 4, at 
B. The No. 4 wire, which safely carries 70 amp. (Table A, Sec. 170), is 
fused at A with a 50-amp. fuse, which will, according to Table A , Sec. 
170, protect a No. 6 rubber-covered wire which safely carries 50 amp. 
Therefore, no fuse is required at C because the No. 6 wire is protected 
by the fuse at A. The No. 8 wire (capacity = 35 amp.) must be fused at 
B with a fuse not greater than 35 amp., since it will not be protected by 
the 50-amp. fuse at A . 








118 


LIGHTING CIRCUITS AND SWITCHES 


[Drv. 3 


170. Table Showing Maximum Allowable Current-carrying 
Capacity Of Solid Copper Wires. (Code Rule 18.) 


B. «& S. Gage 
No. 

Dia. of solid 
wire in mils 

1 

Area in cir¬ 
cular mils 

Table A. 
Rubber insu¬ 
lation, am¬ 
peres 

Table B. 
Varnished 
cloth insu¬ 
lation, am¬ 
peres 

Table C. 
Other insu¬ 
lation am¬ 
peres 

18 

40.3 

1,624 

3 


5 

16 

50.8 

2,583 

6 

• • • • 

10 

14 

64.1 

4,107 

15 

18 

20 

12 

80.8 

6,530 

20 

25 

25 

10 

101.9 

10,380 

25 

30 

30 

8 

128.5 

16,510 

35 

40 

50 

6 

162.0 

26,250 

50 

60 

70 

5 

181.9 

33,100 

55 

65 

80 

4 

204.3 

41,740 

70 

85 

90 

3 

229.4 

52,630 

80 

95 

100 

2 

257.6 

66,370 

90 

110 

125 

1 

289.3 

83,690 

100 

120 

150 

0 

325.0 

105,500 

125 

150 

200 

00 

364.8 

133,100 

150 

180 

225 

000 

409.6 

167,800 

175 

210 

275 

.... 

.... 

200,000 

200 

240 

300 

0000 

460.0 

211,600 

225 

270 

325 


.... 

250,000 

250 

300 

350 



300,000 

275 

330 

400 


.... 

350,000 

300 

360 

450 



400,000 

325 

390 

500 



500,000 

400 

480 

600 



600,000 

450 

540 

680 


.... 

700,000 

500 

600 

760 



800,000 

550 

660 

840 


• • • • 

900,000 

600 

720 

920 


.... 

1,000,000 

650 

780 

1,000 


.... 

1,100,000 

690 

830 

1,080 


.... 

1,200,000 

730 

880 

1,150 



1 , 300,000 

770 

920 

1,220 

.... 

. • « . 

1,400,000 

810 

970 

1,290 

«... 

.... 

1,500,000 

850 

1,020 

1,360 


.... 

1,600,000 

890 

1,070 

1,430 


• . . . 

1,700,000 

930 

1,120 

1,490 


• . . . 

1 , 800,000 

970 

1,160 

1,550 

.... 

.... 

1,900,000 

1,010 

1,210 

1,610 


.... 

2,000,000 

1,050 

1,260 

1,670 


Note.—Fixture Wire Or Flexible Cord of No. 18 B. & S. gage will 
be considered as properly protected when fused with 10-amp. fuses 
(Code Rule 23d). 

171. Fuses Must Not Be Placed In Any Permanently 
Grounded Wire, except that where a two-wire branch or tap, 






















































Sec. 171 ] UNDERWRITERS’ REQUIREMENTS 119 

which is directly connected to lamp sockets, connects to one 
outside wire and to the permanently grounded neutral of a 
three-wire system, both wires of such a tap or branch must be 



Fig. 171. Distribution panel for a 110 220 volt, three-wire grounded-neutral system, 
showing fuse arrangement to comply with Code requirements. 

protected by fuses. A correct arrangement is shown in Fig. 
171. The omission of the fuse in the neutral wire may be 
accomplished by the various methods as shown in Figs. 172, 
173, and 174. 



Service. Switch- 


Grounded 
[Neutral: '■ 


■Service Fuses 


Copper. 



. ■Grounded 
Neutral. . ^ 


CopperStrip 
In Neutral-' 


Fp: Service 
£ Switch 


Buskpar-, 


Fig. 172.—Copper strip, C, inserted in Fig. 173.—Copper strip, C, permanently 
the fuse-block jaws of the neutral and sol- secured to base, substituted for fuse, 
dered thereto. Such a copper strip is 
used in lieu of a fuse in the grounded 
neutral of a three-wire system. 


Note.—Suppose A Three-wire, Grounded-neutral System Had 
A Fuse In The Neutral and had no fuses in the two-wire branches, 
as shown in Fig. 175. Then, if a short-circuit occurred, say at D, 
fuse A of the neutral might be “ blown,” or ruptured. This would 
result in a potential difference of 220 volts being impressed on circuit C. 



























































































120 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 3 


The least damage that could then occur would be the destruction of all 
lamps connected to circuit C. Provisions are therefore made to prevent 



Plug (Not 
.'-•-A Fuse) 


Plug Fuses 


Fig. 174. —The plug, P, when screwed into the neutral-wire cutout provides a means 
of bridging this cutout, thus connecting the neutral through this cutout, solid.” 
(After installation the manufacturer recommends that the plug should be soldered 
therein. Bryant Electric Co.) 


such an occurrence by so constructing the neutral that it will always 
remain intact except when the outside wires are opened by the switch 
(see Sec. 137). 


HO - 720 * Volt Supply 



Fig. 175. —Showing probable results in a 110-220 volt, three-wire, grounded-neutral 
system when not fused according to Code requirements. 


172. Branch And Tap Circuits Must Be So Fused (Code 
Rule 23d) that (with the exceptions recited below) no set of 
small motors, small heating devices, or incandescent lamps, 
whether grouped on one or several fixtures or pendants, 
requiring more than 660 watts, will be dependent upon one 
cutout. On a purely lighting circuit, 16 medium or 25 
candelabra size sockets are, in the interpretation of this rule, 
assumed not to require more than 660 watts. Branch and tap 


































Sec. 173] UNDERWRITERS’ REQUIREMENTS 121 

circuits usually consist of No. 14 B. & S. gage wire, which, if 
rubber-covered, has a safe carrying capacity (Table A, Sec. 
170) of 15 amp. It would seem permissible to protect such 
a circuit with 15-amp. fuses. However, there is usually 
attached to the circuit No. 18 flexible cord or fixture wire, 
which has an actual safe current-carrying capacity of only 
3-amp. If a short-circuit or ground occurred on this flexible 
cord, or within a socket, the No. 18 wire might attain a suffi¬ 
cient temperature to incur a dangerous fire hazard before the 
15-amp. fuse would burn out. Such a circuit may be (Code 
Rule 25a), and usually is, fused with 10 amp. fuses. Another 
reason for the 660-watt rule is that the small switches, such 
as single-pole, key-socket, three- and four-way switches, which 
are ordinarily used on such circuits, are not designed for 
rupturing any considerable amount of energy, and must be 
protected by suitable fuses which will limit the energy through 
them. 

Note.—It Is Possible That The 1923 Code (see Sec. 118) will 
permit a maximum of 12 outlets on one branch circuit and that such 
branch circuits may be fused as follows: 15-amp. fuse at 125 volts or 
less; 10-amp. fuse at 126 to 250 volts. 

173. Where Only One Socket Or Receptacle Is Used On A 
Circuit, (Code Rule 23d) the maximum permissible wattage 
for the final fuse in that circuit shall not exceed the capacity, 
in watts, for which the socket or receptacle is approved. 

Example. —If a single flush receptacle, which is approved for 660 watts, 
is used on a 110-volt circuit, the fuse protecting that circuit must not 
exceed: 660 -f- 110 = 6 amp. This is to prevent an overloading of the 
receptacle which could be done by connecting thereto an energy-consum¬ 
ing device having, say a rating of 10-amp. at 110 volts. 

174. Exceptions May Be Made, By Obtaining Special 
Permission, To The 660-Watt Rule as follows: (Code Rule 
23d). 

A. Where No. 14 wire is carried direct into keyless sockets 
or receptacles, and where the location of such sockets or 
receptacles is such as to render unlikely the attachment of 
flexible cords thereto, the circuit may be so arranged that not 


122 


LIGHTING CIRCUITS AND SWITCHES 


[Drv. 3 


more than 1,320 watts (32 sockets or receptacles) may be 
dependent upon the final cut-out. 

B. Circuits supplying sockets or receptacles of the Mogul 
type may be so arranged that not more than 4,000 watts will 
be dependent upon the final cut-out, provided that: (a) The 
location of the sockets and receptacles is such as to render unlikely 
the attachment of flexible cords thereto. ( b ) That the sockets 
do not have a fibre or paper lining. 

Note.—Mogul Sockets And Receptacles, must be wired with 
conductors of a size not less than No. 12 B. & S. gage. The length of 
the taps from circuit wires to the point of suspension of such sockets, 
receptacles, and fixtures, must not exceed 18 in. 

Note. —It Is Possible That The 1923-Code (see Sec. 118) will 
permit branch circuits supplying Mogul sockets to be fused as follows: 
40-amp. fuses at 125 volts; 20-amp. fuses at 126 to 250 volts. 

175. The Rated Capacity Of Fuses Protecting Branch 
Circuits shall not exceed the values given in the following 
table (Code Rule 23 d): (See notes about 1923 Code under 
Secs. 172 and 174.) 


Voltage 

Circuit not exceeding 

660 watts 

1,320 watts 

125 or less. 

10 amp. 

6 amp. 

20 amp. 

10 amp. 

125 to 250. 



Note.—Fused Rosettes May Be Used only for open work in large 
mills (Code, Rule 23d). Approved link-fused rosettes are not permitted 
for use at pressures exceeding 125 volts. Approved enclosed-fused 
rosettes are not permitted for operation at over 250 volts. For both 
link-fused and enclosed-fused rosettes, the fuse in the rosette must not 
have a rating greater than 3 amp.; a fuse of over 25-amp. capacity must 
not be used in the branch circuit containing such rosettes. 




















Sec. 176] 


UNDERWRITERS ’ REQUIREMENTS 


123 


176. Table Showing Size Of Conduit For The Installation 
Of Wires And Cable. (Code, Rule 28 i). 


V 

Size of conductor. B. & S. 
gage 


Number oi 

conductors 

in one conduit 


1 

2 

3 

4 

5 

6 

7 

8 

9 


Minimum size 

of conduit in inches 


1 

14 

K 

K 

K 

K 

K 

1 

1 

1 

1 

12 

K 

K 

K 

K 

K 

1 

1 

1 

IK 

10 

K 

K 

K 

l 

l 

1 

IK 

IK 

IK 

8 

K 

K 

1 

l 

l 

IK 

IK 

IK 

IK 

6 

K 

l 

IK 

IK 

IK 

l K 

2 

2 

2 

5 

K 

IK 

IK 

IK 

1 K 

2 

2 

2 

2 

4 

% 

IK 

IK 

IK 

2 

2 

2 

2 

2K 

3 

H 

IK 

IK 

l K 

2 

2 

2 

2 K 

2 K 

2 

K 

IK 

i K 

i K 

2 

2 

2K 

2 K 

2 K 

1 

% 

IK 

i K 

2 

2 

2 K 

2 K 

3 

3 

0 

l 

IK 

2 

2 

2K 

2 K 

3 

3 

3 

00 

l 

2 

2 

2 K 

2 K 

3 

3 

3 

3 K 

000 

l 

2 

2 

2K 

3 

3 

3 

3 K 

3 K 

0000 

IK 

2 

2 K 

2 K 

3 

3 

3 K 

3 K 

4 

200,000 C.M. 

IK 

2 

2K 

3 

3 

3 

3K 

3K 

4 

225,000 

IK 

2 K 

2K 

3 

3 

3K 

3 K 

4 

4 

250,000 

IK 

2K 

2 K 

3 

3 

3K 

3 K 

4 

4 K 

300,000 

IK 

2 K 

3 

3 

3 K 

3 K 

4 

4 K 

4 K 

350,000 

i K 

2 K 

3 

3 K 

3 K 

4 

4 K 

4 K 

5 

400,000 

IK 

3 

3 

m 

4 

4 

4K 

5 

5 

450,000 

IK 

3 

3 

3K 

4 

Mi 

Mi 

5 

6 

500,000 

IK 

3 

3 

3 K 

4 

4 K 

5 

5 

6 

550,000 

l K 

3 

3K 

4 

4K 

5 

5 

6 

6 

600,000 

2 

3 

3 K 

4 

4K 

5 

6 

6 

6 

650,000 

2 

3 K 

3 K 

4 

4 K 

5 

6 

6 

6 

700,000 

2 

3 K 

3 K 

4K 

5 

5 

6 

6 


750,000 

2 

3 K 

3 K 

4M 

5 

6 

6 

6 


800,000 

2 

3 K 

4 

4H 

5 

6 

6 

6 


850,000 

2 

SK 

4 

4H 

5 

6 

6 


1 ' 

900,000 

2 

3 K 

4 

4 K 

5 

6 

6 



950,000 

2 

4 

4 

5 

6 

6 

6 



1,000,000 

2 

4 

4 

5 

6 

6 




1,100,000 

2 K 

4 

4M 

6 

6 





1,200,000 

2 K 

4K 

4H 

6 

6 





1,250,000 

2 K 

4M 

4K 

6 

6 





1,300,000 

2 K 

4H 

5 

6 

6 





1,400,000 

2 K 

4H 

5 

6 






1,500,000 

2 K 

4H 

5 

6 






1,600,000 

2K 

5 

5 

6 






1,700,000 

3 

5 

5 

6 






1,750,000 

3 

5 

5 

6 


1 

. 



1,800,000 

3 

5 

6 

6 






1,900,000 

3 

5 

6 







2,000,000 

3 

5 

6 




i 












































































124 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 3 


Note.— The values contained in the above table apply only to complete 
conduit systems. They do not apply to short sections of conduit used 
for protection of exposed wiring from mechanical injury. 

176A. Polarity Identification of Rubber-covered Wire 

is shown in Fig. 175A. Rule 26a of the 1920 Edition of 


Line 


Line--. 






r 

4j 

Outlet---y , 

— 


1 


-k-Switch 




i 


I-Single-Pole Switch 


k- Switch Outlet 

E-Single-Pole Switch 



if 


m.'S witch 
.■Line 


Outlet - > 


Ur 






y 



h- 

■0 

* 5w,tch Outlet-y - 



f.'Line 


1 

• 


ffi-Single-Pole Switch 


E-Single-Pole Switch 




i siiLme 







1 — 




[ 

qL-o 

rr 

u 

"*Qut- ; 



; 

*“Q 

1 


•±0ut- 1" 

ul 

1 

Switches 

"< lets 



> 1 

1 

0 51 

<. Ml 

■ Sw/tc 

hes 

lets-y 

1 1 



V'Two-Sang Single-Pole Switches VI-Two-Gang Single-Pole Switches 


fti 




'Switches 


y-0ut -: 

1 Lets *5 


Line ; 


o to 

m 


■Switches 


SOut- ; 
i lets -■> 


VU'Two-Gang Single-Pole Switches . YDI-Two-Gang Single-Pole Switches 


'Line 

p"Switches -4 






Outlet 




vLin e 

— ^--Switches -4 


Line--. 


K~ Three-Way Switches 


Outlet. 




U 


X - Three-Way Switches 





k‘ 

"OYHTCnCS'X 

5^ 

Outlet. \, 
Line : >i 

O 

QJ 


4 


2I-Three-Y</ay Switches 


j.--Switches-^ 


I Outlet-. 


'v -* 


■■Line 




XU - Three-Way Switches 



X2~Mains 


k" Switches- -a 


r ■ 


<? <2 



Outlet-. ; 

> O 

s\ 

1 


Line -> i 



-<-• 


XE~ Three-Way Switches 



Switches 





k' 

[ ttt 

L 

To 

Outlet. \ , 

► 


1 

■Line 

S 





XH - Three-Way Switches 



XVI - Mains 


Fig. 175 A .—Showing how “polarity-identification” 

in interior wiring. 


rubber-covered wire is connected 


the Code reads as follows: “ (After July 1, 1921) One conductor 
of twin rubber-covered wires of No. 12 and No. 1 4 sizes, arid of 
twisted pair wires of armored cable must have a continuous 
identifying marking readily distinguishing it from the other 
conductor. When one of the circuit wires is to be grounded, 






















































































































































































































































































































Sec. 176A] UNDERWRITERS’ REQUIREMENTS 


125 


the ground connection must he made to this identified wire and 
as prescribed in Nos. 15 and 15A.” In the accompanying 
diagrams (Fig. 175A) illustrating the use of the marked wires 
referred to in the above rule, the heavy line represents the 
black-covered and live wire, and the light line, the identified 
and grounded wire. 

Note. — It Is Probable That The 1923-Code (see note under Sec. 
118) will require: “For conductor sizes No. 8 and smaller, the neutral 
conductor on all three-wire circuits and one conductor on all two-wire 
circuits shall have a continuous identifying marker readily distinguishing 
it from the other conductors.” Furthermore, “When one of the circuit 
wires is grounded, the ground connection must be made to this identified 
wire.” 

QUESTIONS ON DIVISION 3 

1. What is the National Electrical Code? 

2. Why is compliance with Code requirements usually necessary? 

3. What constitutes an approved device? 

4. What markings must be placed on knife switches? 

5. What properties must knife-switch bases possess? 

6 . What are the requirements which apply to knife-switch bases? To open-link-fuse 
bases? 

7. Show by sketch, the meaning of break distance and of distance between parts of 
opposite polarity. 

8 . Why are 300-amp. knife switches permitted for use on switchboards only? 

9. Explain, by sketch, parts mounted on same surface; parts mounted clear of surface. 

10. How must the jaws of a knife switch be secured to the base? Why? 

11 . How may switches which have a rating in excess of the maximum approved 
enclosed-fuse rating be fused with enclosed fuses? 

12 . What is a switch barrier? What is its function? Illustrate with a sketch. 

13. Why must the insulation distance be greater between the break-jaws of a knife 
switch than between the hinge-jaws? 

14. Show by sketch how the required spacing may be obtained between the hinge- 
jaws of a front-connected, multi-pole switch. 

15. What is a quick-break switch? In excess of what current and voltage rating is 
its use required? 

16. What is a service switch? What are the requirements which pertain to its 
location? 

17. Show by sketch how a service switch must be wired in respect to its service fuses 
and meter. What are the exceptions thereto? 

18. When must, and when may not service switches be enclosed? 

19. What is considered to be an accessible place for a service switch? 

20. Show by sketch the position in which a single-throw knife switch should be 
vertically mounted with respect to the source of voltage. A double-throw switch. 

21. How should a knife switch be wired as regards the blades? Make a single sketch 
graphically answering questions 17, 20 and 21. 

22. Why should a single-pole switch never be used in the grounded-neutral of a three- 
wire main or feeder? 

23. Show by a sketch and explain why a double-pole switch is preferable to a single¬ 
pole for use in controlling a two-wire branch of a three-wire, grounded-neutral system. 

24. Name the various types of switches which must be considered as single-pole 
switches to comply with Code requirements. 


126 


LIGHTING CIRCUITS AND SWITCHES 


[Diy. 3 


25. Show by sketches how the following flush switch boxes should be installed in the 

lath-nnd-plaster partition of: (a) A new building . (6) A finished building. Also how 

the box for a baseboard outlet should be installed in a partition in a new frame building. 

26. Why are snap switches preferable to knife switches for controlling lighting 
circuits of small capacity? 

27. How may fuses be classified? 

28. Why are link fuses frequently undesirable? Why are they well adapted for 
certain services? 

29. With what per cent, of the maximum current which they can carry indefinitely 
are link fuses stamped? 

30. Where may link fuses be used? 

31. Name three types of approved enclosed-fuse cutout bases, and make a sketch and 
give the ratings of the terminal or holder for each. 

32. What is a sealable service and meter cutout? 

33. What are the markings which must appear on approved enclosed-fuses of the 
cartridge type? 

34. Write a summary of the enclosed-fuse classification. 

35. In generally-accessible service cutout boxes, why is the wiring such that the 
fuses are “dead” when the switch is open? 

36. Explain by sketch why fuses should not be placed in a permanently grounded 
neutral and why each conductor of the two-wire branch of a three-wire grounded-neutral 
system should be fused? 

37. Give reasons for the 660 -watt rule. What are 


two exceptions to this rule? 


DIVISION 4 


SINGLE- AND MULTI-POLE SWITCH CIRCUITS 

177. The Single- And Multi-pole Switch Circuits which are 
described in this division, include only those circuits which 
may be controlled by one-, two-, and three-pole switches, as 
are defined in Secs. 45 to 48. Both single- and double-throw 
switches are discussed. Although three-way, four-way, 
electrolier, and series-parallel switches are considered by the 
Code (Div. 3) as single-pole switches, their applications (see 
Index) are treated elsewhere in this book. 

178. The Most Frequent Use For The Single-pole Switch 
(Fig. 176) is probably for controlling a single lamp (Fig. 177) 
or a group of lamps (Fig. 178). 



Fig. 176.—Showing use of single- and double-pole switches in a small residence. 

Note.—Lighting-circuit Control With Knife Switches Is Usually 
Undesirable except in service or distribution boxes. However, knife 
switches are sometimes so used in emergencies, and also in laboratories 
and test-rooms. Although the Code will permit the use of a knife 

127 
























































































128 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 4 


switch in any location provided it is properly installed, snap switches 
are, in locations other than those mentioned above, usually less expensive, 
more sightly, and also more convenient as regards installation and opera- 



- -Single-Pole Switch 


Fig. 177. —Single-pole switch controlling circuit of a single lamp. (Frequently a key 

socket.) 

tion. It should be noted (see Div. 2) that snap switches, both in the 
rotary and push-button types, are manufactured which will, within their 
capacities, perform practically the same functions as will the various 
equivalent knife switches. 



Fig. 178.—Single-pole switch controlling a group of lamps. 


179. Two Single-pole Switches Connected In Series are 

shown in Fig. 179. The lamps may be extinguished with 
either switch, but both switches must be “on” to light the 
lamps. This method of connections may be employed where 



Lights May Be Extinguished By Either Switch. 

Both Switches Must Be Closed To Light The Lamps. 


Fig. 179.—Two single-pole switches connected in series. 

it is desired that the lighting of lamps, be supervised from a 
remote point, R. That is, if it is desired that it be made 
impossible to light lamps L by the operation of P, switch R, 
which may be located anywhere, is left open. With R open, 































Sec. 180] SINGLE- AND MULTI-POLE CIRCUITS 


129 


the circuit cannot be closed with P. The same control as that 
of Fig. 179 is provided by connecting the lamps between the 
switches as shown in Fig. 180. Although in Fig. 180 both 
sides of the line can be opened by the two single-pole switches, 
*Si and $ 2 , this arrangement does not comply with the Code 
requirements relative to a double-pole switch opening both 
sides of the line. 



Lights Hay Be Extinguished By Opening Either Switch./ 
Both Switches Must Be Closed To Light The Lamps. 


Fig. 180.—Two single-pole switches connected in series with lamps in parallel between 

the switches. 

180. Two Single-pole Switches Connected In Parallel are 

shown in Fig. 181. Lamps thus controlled may be lighted by 
either switch, but both switches must be “off” to extinguish 
the lamps. Such an installation may be used where it is 
desired that the lighting (but not extinguishing) of a lamp, or 
of a group of lamps, be controlled from a distant location. 
This is (Sec. 56), in effect, and elementary master switch. 



Lamps May Be Lighted By Either Switch 
Both Switches Must Be Open To Extinguish Lights 


Fig. 181.—Two single-pole switches connected in parallel. 

181. Two Single-pole Switches Using One Wire As A 
Common Return (Fig. 182) may be used for controlling two 
groups of lamps. If the lamps are located near each other, as 
on a chandelier, a wire-saving, which is equal to the distance 
from the switch to the chandelier, will be effected with the 
wiring of Fig. 182. This arrangement is essentially equivalent 

9 





























130 


LIGHTING CIRCUITS AND SWITCHES 


[Drv. 4 


to that of a two-circuit electrolier switch (Sec. 294) and may be 
used in lieu thereof. A convenient switch for this purpose is 
described in Sec. 90. 



Fig. 182. —Two single-pole switches utilizing a common return, C, to control two 
groups of lamps. (Group B' is controlled by switch B. Group A' is controlled by 
switch .4.) 

182. Connections For Two Single-pole Switches Connected 
In Series To Obtain Restricted-selective Control Of Lamps 

(Sec. 17) are shown in Fig. 183. Closing and opening switch 
B will alternately light and extinguish lamp B'. With B 
closed, successive operations of switch A will alternately 
light and extinguish, simultaneously, lamps A'. With A 



Fig. 183. —Group of lamps controlled by two single-pole switches. (Opening and 
closing B alternately lights and extinguishes B'. If B is closed, closing and opening A, 
alternately lights and extinguishes lamps A'. If A is closed, closing and opening B, 
alternately lights and extinguishes all lamps.) 

closed, successive operations of B results in simultaneously 
lighting and extinguishing of all lamps in the entire group. 
As in Fig. 182, only three wires are required from the switches 
to the lamps. Although only a one-and-four-lamp control of 
a five-lamp group (Fig. 183) is shown, any two-group com¬ 
bination on any number of lamps may be arranged. A two- 
button push-switch, which is so connected internally that the 




























Sec. 183] SINGLE- AND MULTI-POLE CIRCUITS 


131 


above-described control is provided, and which is contained 
in a single porcelain cup, is described in Secs. 90 and 299. 

183. A Single-pole, Double-throw Switch May Be Used 
To Provide Dimming Of Lights as shown in Fig. 184. When 
the switch, D, is open, all lamps, A' and B', burn at one-half 
normal voltage. When the switch is closed to A, lamps A' are 
extinguished and lamps B' burn at full voltage. By closing 



the switch to position B } group B' is extinguished and group A' 
burns at full voltage. Note that the single-pole, double¬ 
throw switch, D, will not, when connected as shown, extinguish 
all of the lights; a second switch, S, must be provided for this 
purpose. This arrangement may be applicable for night or 
pilot-light service for long hall-ways or spacious rooms. It 
may also be used in store rooms, and other locations where it 
may be desirable to have available either an evenly-distributed 



Fig. 185.—Single-pole double-throw switch connected so that only one group of lamps 

can be lighted at a time. 


dim light or a more-concentrated bright light. It should be 
remembered that when incandescent lamps are burned at 
much less than normal voltage, they are very inefficient. With 
one-half normal voltage impressed on a lamp, its light output 
is much less than one-half normal. In fact, at half voltage, 
the filament of a tungsten lamp is only bright red in color. 

184. Single-pole, Double-throw Switch Connections For A 
Restricted Lighting Circuit (Sec. 15) where only one group of 
lamps can be lighted at any one time are shown in Fig. 185. 








































132 


LIGHTING CIRCUITS AND SWITCHES 


[Drv. 4 


With the switch, S, in the “open” position, neither group of 
lamps will burn. If the switch is closed to position A, group 
A' is lighted and B' is extinguished; if closed to position B , 
group B' is “on” and A' is “off.” 

185. A Single-pole, Double-throw Switch Connected To 
Provide Load-balancing On A Three-wire, Direct-current 
Circuit; A Three-wire, Single-phase Circuit; Or On A Three- 
wire, Two-phase Circuit is shown in Fig. 18G. In /, the load 
is carried by side-circuit AB; in II, it is carried by BC. Thus, 
the switch, S, may be thrown so that the lighting-load will be 
carried by either of the “outside” wires and the neutral. If 



I-Load Carried By A B 


c 

B 

A . 

T1 -+ A A .rY'rS" 




1 



F-Load Carried By B G 


Fig. 186 . —Single-pole, double-throw switch connected to provide load balancing on 
a three-wire direct-current circuit, a three-wire single-phase circuit or a three-wire two- 
phase circuit. In I the load, L, is carried by side circuit BA. In II the load is carried 
by side circuit CB. 

either of the outside wires becomes broken, the load may be 
switched to the other outside wire and the neutral, and so 
carried until repairs are made. Or, if the load imposed b} r 
receivers on some other part of the system becomes excessive 
on one of the side circuits, the load of the receiver-group, L, 
(Fig. 186) may be shifted by throwing S to the other side 
circuit. Thereby balance may be partially or completely 
restored. 

186. To Assist In Balancing The Load On Three-phase 
Lighting Mains, Single-pole, Double-throw Switches May Be 
Used as suggested in Fig. 187. Two switches are required for 
each branch which is to be shifted from phase circuit to phase 
circuit. With the two switches arranged on the single-phase 
branch circuit as shown, the load on the branch circuit may be 
connected between any of the three sets of phase-wires of the 































Sec. 187] SINGLE- AND MULTI-POLE CIRCUITS 133 

three-phase main. By closing the switches to the positions 
(I, II, or III, Fig. 187) shown at A', B', or C', the branch- 
circuit load, L, will be carried, respectively, by phase circuits 
A, B, or C. Note that if the switches are either both “open, ” 
or both closed to the right, the lights will be extinguished. 



Fig. 187.—Two single-pole double-throw switches connected for balancing load on 
three-phase lighting mains. If both switches are open, or are closed to the ‘‘right,” 
all lights will be “off.” 


187. Control Of Lights From Two Locations With Two 
Single-pole, Double-throw Knife Switches may be provided 
as shown in Figs. 188 and 189, or in Figs. 190 and 191. In 
Figs. 188 and 189, only one side of the line is connected directly 



Fig. 188.—Two-location control of lamps with two single-pole double-throw switches. 
(Only one side of line, Li, connected to switches.) 


to the switches, while in Figs. 190 and 191, both sides are 
connected directly to each switch. 


Note.—When Single-pole, Double-throw Knife Switches Are 
Used For Two-location-lighting-control, (Figs. 188, 189, 190 and 









































































134 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 4 


191), they should be so mounted that the throw of the switches will be 
horizontal rather than vertical (Sec. 140). For successful operation of 



Fig. 189. —Single-pole, double-throw knife switches used instead of three-way switches 

for two-location control. 

such an arrangement, both switches must always be closed. That is, if 
the lights are extinguished at switch A, (Fig. 188) by opening contact c, 


Travelers v . 



' Single-Pole , Double-Throw Switches ' 


Fig. 190.—Two-location control of lamps with two single-pole double-throw switches. 

(Both sides of line connected to switches.) 

the switch blade should then be closed to contact a. Otherwise, the 
lamps cannot be lighted by switch B. 



Fig. 191.—Single-pole double-throw knife switches used for two-location control. 


188. One Of The Most Common Applications Of Multi-pole 
Switches is (Fig. 192) at distribution centers. The three-pole 
switch, T, controls the supply circuit which supplies the distri- 
































































Sec. 189] SINGLE- AND MULTI-POLE CIRCUITS 


135 


bution center, and therefore operates to extinguish all lights 
controlled by that center. The double-pole switches, D, 
control the branches or sub-feeders (see Sec. 142). 


.-Double-Pole Knife Switches-, 



Fig. 192.—Showing application of three-pole and double-pole switches on a panel. The 
middle pair of fuse clips contains a solid copper conductor—not a fuse. 

189. The Usual Double-pole Switch Connection is shown in 
Fig. 193. This is the method which is ordinarily used for the 
control of outdoor circuits, circuits located in damp places 
(Sec. 141), and for installations wherein it is necessary, or 
desirable, that both legs of the circuit be disconnected by the 
opening of the switch. 



Fig. 193.—Ordinary double-pole switch connections for lighting-circuit control. 

190. Two Double-pole Snap Switches May Be Connected 
In Parallel as shown in Fig. 195-7. This gives a result similar 
to the single-pole-switch arrangement of Fig. 181. Such an 
arrangement enables the lamps to be lighted by closing either 
switch, but both switches must be open to extinguish them. 
Common errors in connection, which will result in short- 
circuit as soon as both switches are closed, are shown in Fig. 
195-77 and 777. Three or more double-pole switches may be 
connected in parallel by the method of Fig. 194. 

Note.—Single-throw, Double-pole Knife Switches May Be 
Connected To Obtain The Same Control Effect As That Afforded 













































136 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 4 


By Double-pole Snap Switches. However, errors (Sec. 198) in con¬ 
nections, which will result in a short-circuit, are not so likely to be made 
when knife switches are used as when snap-switches are used. 

Note.—For The Usual Connections Of A Double-pole Snap 
Switch, the terminals marked “L” may be used as a guide; the line-wires 



Fig. 194.—Method of connecting three or more double-pole switches in parallel. 
(Lamps may be lighted by closing any switch. All switches must be open to extinguish 
lights.) 


should be connected thereto. However, when making special connections 
with such a switch, or to any switch to which both sides of the line are 
connected, extreme caution must be observed to prevent a short-circuit 
as in Fig. 195-///. 





Fig. 195.—Correct and incorrect methods of connecting two double-pole snap switches - 
in parallel. (Closing both switches in II or III will result in a short circuit.) 

191. Double-pole Switches May Be Connected In Series as 

as shown in Fig. 196. Lamps thus controlled may be extin¬ 
guished by opening either switch, but both switches must be 



















































Sec. 192] SINGLE- AND MULTI-POLE CIRCUITS 


137 


closed to light the lamps. The result is similar to that 
obtained with the single-pole-switch arrangement of Fig. 179. 



Fig. 196.—Double-pole switches connected in series. (Lights may be extinguished by 
opening either switch. Both switches must be closed to light lamps.) 


192. A Series-parallel Method Of Connections For Double¬ 
pole Switches (Fig. 197) may be utilized for progressive or 
selective lighting, as in the corridors of basements. Neither 
lamp-group B' nor C' can be lighted until switch A is closed. 
However, all lights may be extinguished by opening A. 
Switches B and C, which control lamp-groups located in 
different corridors or passageways, should be so located with 
respect to the lamp-group A' that they are rendered visible 
by the light from A'. Thus, only the pathway which is 



Fig. 197.—Double-pole switches connected in series-parallel, for use in progressive 
lighting of damp basements or out-door circuits. 


traversed as a person enters and leaves the corridor, may be 
lighted, without the necessity of lighting all of the lamps on 
the branch circuit. 

193. A Double-pole Switch May Be Connected To Provide 
Single-pole-switch Control as shown in Fig. 198. That is, 
although a double-pole switch, DP, is used, only one side of 
the line is disconnected when it is open. In Fig. 199 where a 
room has branches, R, in each end-partition and the specifica¬ 
tions require that the switch be located near the door in the 






































138 LIGHTING CIRCUITS AND SWITCHES [Div. 4 

center of the room, the principle outlined above may sometimes 
be applied to effect a wire-saving. By using a double-pole 
switch, connected as shown at A, instead of a single-pole, 



Fig. 198.—Double-pole switch connected as single-pole. 


as shown at B , the length of wire, D, may be eliminated. 
Note that the double-pole switch disconnects only one side 
of the line from the source of voltage. 



Fig. 199.—Showing how a wire saving may sometimes be effected by using a double¬ 
pole switch, A, instead of a single-pole switch B. 

194. A Method Whereby One Double-pole Switch May Be 
Used For Controlling Two Distinct Circuits is shown in Fig. 
200. One of the circuits is completed through one blade of the 
double-pole switch, S. The other circuit is completed through 
the second blade. The use of a circuit arrangement such as 
that shown, wherein a low-voltage battery-operated signal 
circuit is carried into the same double-pole switch with a 110- 
volt lighting circuit is not sanctioned by the Code (Rule 16e 























































Sec. 195] SINGLE- AND MULT I-POLE CIRCUITS 


139 


and 85/), and will not be approved by inspectors. In Fig. 200, 
as long as the lamps L are lighted, the vibrating bell, B, will 
ring. Thus, the bell provides an audible signal of the use of 
energy by the lamps. 


Double-Pole Switch 


HO-Volf c 

LightingCircuit \ ~ 


Incandescent 
Lamps — 



battery---. 


'■Low-Voltage 
Signal Circuit. 



v 


-Vibrating 
' Bell 


Fig. 200.—One double-pole switch controlling two distinct circuits. 


195. Restricted-selective Control May Be Provided By Two 
Double-pole Switches (Sec. 17) by the connections which are 
shown in Fig. 201. If both switches, A and C, are open, then 
lamps A’ and B' may be lighted by closing switch A, or lamps 
B' and C' may be lighted by closing switch C. If both switches 
are closed; C' may be extinguished by opening C, or, A' may be 



Fig. 201.—Selective control provided by two double-pole switches. (Lights A' 
and B’ may be lighted by closing switch A. Lights B' and C' may be lighted by closing 
switch C. C and A are respectively extinguished by opening C and A. Both switches 
must be open to extinguish B'.) 

extinguished by opening A. With both switches open, all 
lights are extinguished; and with both switches closed (as 
shown in Fig. 201), all lamps are lighted. It is, of course, 
apparent that a lamp-group comprising a reasonable number 
of lamps which are connected in parallel may be substituted 
for either A ', B', or C '. 





























140 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 4 


196. Series-parallel, Or “Dimming,” Control may be 

obtained as illustrated in Figs. 202 and 203. When the switch 
is closed, all lamps have the full line voltage impressed across 
their terminals. When the switch is open the lamps burn at 
one-third line voltage, and, consequently, only about one-third 
of the normal quantity of energy is consumed. The branch- 



Fig. 202.—Double-pole switch connected to provide series-parallel control for three 
groups of lamps, A, B and C. (When switch is closed, all lamps have the full line- 
voltage impressed across their terminals. When switch is open the lamps burn at % 
line voltage if groups A, B and C, each contain the same total wattage-rating.) 

circuit switch at the distribution center may be used to 
extinguish all lights. Such an arrangement is particularly 
applicable in long corridors or hall-ways, in large areas such as 
machine shops, storage rooms, and the like, where at certain 
times it is desired to secure a distributed dim light for burglar 
protection or night-watchman’s use, and at other times, to 


yDouble-Pole Switch 



Fig. 203.—Showing how a wire saving may be effected in double-pole-switch connec¬ 
tions which provide series-parallel or dimming control. 

secure the usual illumination. Where all of the lamps so 
controlled are located in one row, the arrangement shown in 
Fig. 203 may effect a wire-saving over that in Fig. 202. If all 
of the lamps of any one group, either A, B, or C, burn out, all 
of the lights on the circuit will be extinguished as long as the 
switch is open. The total wattage of the lamps in each group 











































Sec. 197] SINGLE- AND MULTI-POLE CIRCUITS 


141 


(A, B, and C) should be always kept the same. When 
tungsten lamps burn at one-third normal voltage, the filament 
is only a dull red. 

197. A Wire-saving Method Of Adding A Pilot Lamp Or A 
Group Of “Night-and-day” Lamps To An Existing Double¬ 
pole Switch Installation is outlined in Figs. 204 and 205. In 



Fig. 204.—Double-pole switch with shunt, S, connected to diagonally-opposite binding- 
posts. (Lamp L cannot be extinguished by the switch.) 

Fig. 204, the pilot lamp, L, completes its circuit through one 
conductor, MN, of the group of lamps, G. A wire-saving, 
which is approximately equal to the distance from the switch, 
D, to the lamp, L, is thereby effected. The shunt, S, which 
is connected to opposite binding posts of the switch, D, 
renders it impossible to extinguish L by opening D. Thus, 
lamps G may be extinguished by opening D, while the pilot 



Fig. 205.—Double-pole switch with shunt, S, connected to diagonally opposite binding 
posts. (Lamps L cannot be disconnected from source of voltage by switch D.) 

lamp, L, remains lighted. In Fig. 205, the circuit arrangement 
is essentially the same as that of Fig. 204. However, in Fig. 
205, alternate lamps, L, of the group are constantly connected 
to the line, LiL 2 . Lamps G (Fig. 205) may, therefore, be 
extinguished by opening D, while lamps L remain burning. 
This method is frequently employed where it is desired to 
subdivide the lamps on a long hall-way circuit so that one-half 
of the lamps may be lighted during the day, and all of them at 






































142 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 4 


night. All lights are turned out by the branch-circuit switch 
at the distribution center. It may sometimes be found more 
convenient to omit the shunt (S, Figs. 204 and 205) and make 
the connections in the manner indicated by the dotted line, 
MOP, Fig. 204. 



Fig. 206.—Incorrect method of connecting a double-pole switch. (Only one side of the 

line is disconnected by opening the switch). 

198. Some Of The Errors Which Are Likely To Be Made 
In Connecting Double-pole Switches are illustrated in Figs. 
206, 207, and 208. The switch, when connected as in Fig. 206, 



Fig. 207.—Showing incorrect method of connecting a double-pole switch. (Line is 

short-circuited when switch is closed.) 

will operate to open (Sec. 143) only one side of the line. If 
the connections are made as shown in Figs. 207 and 208, a 
short-circuit will result upon closing the switch. 



Fig. 208.—Showing incorrect method of connecting a double-pole switch. (Line 
is short-circuited when switch is closed. The circuit wires have been connected in¬ 
correctly at M or N.) 

199. Restricted-selective Control May Be Provided By A 
Double-pole, Double-throw Switch (Fig. 209). This control 
arrangement is sometimes called electrolier control (Sec. 17). 
By closing the switch to position A ' (Fig. 209), lamps A only 






































Sec. 200] SINGLE- AND MULTI-POLE CIRCUITS 


143 


are lighted. If the switch is thrown over and contact made 
with the opposite pair of jaws, B', all of the lamps, A and B 
will be lighted. All lights may be extinguished by leaving the 
switch in the open position—not contacting with either pair 
of break-jaws. However, it should be noted that when the 
switch is in the open position, only one side of the line, L 2 , is 



Fig. 209.—Electrolier control provided by double-throw double-pole switch. (By 
closing switch-blades to position A', lamps A are lighted. All lamps are lighted when 
switch is closed to position B'.) 


disconnected from the lamps. Even when the switch is open, 
lamp-group A connects directly to line L h and lamp-group B 
connects to Li through group A. 

200. A Double-pole, Double-throw Switch May Be Used To 
So Control Two Groups Of Lamps That Only One Group 
Can Be Lighted At A Time (Figs. 210 and 211). In Fig. 210, 
lamps A are lighted and lamps B extinguished by closing the 



Fig. 210.—Double-pole double-throw switch connected for restricted lighting circuit. 
(Only one group of lamps can be lighted at a time. With switch-blades in position A', 
lamps A are lighted. Lamps B are lighted and lamps A are extinguished when blades 
are closed to position B'.) 

switch to position A'; lamps B are lighted and A extinguished 
by closing the switch to position B'. When the switch is 
either open, or closed to B', lamps A are completely isolated 
from the line, LiL 2 , and are, therefore cut “dead. ” However, 
only one side of the line—side Li —can be disconnected 
from group B ; the other side of B is permanently connected 
to L 2 . Four wires are required in the run between the switch 
and the lamps. In Fig. 211, the same control is provided as 




































144 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 4 


that in Fig. 210. However, it should be noted that in Fig. 211 
only three wires are required from the switch to the lamps; also 
that only one side of the line—side L i—can be disconnected 
from either lamp A or B. 



Fig. 211. —Restricted lighting circuit controlled by double-pole, double-throw 
switch, requiring only three wires from switch to lamps. (Blades closed to position A' 
lights lamp A. Blades closed to position B' lights lamp B. Blades in the open position, 
all lamps off.) 


201. Double-pole, Double-throw Switch Connections for 
Restricted-selective Control of 110-volt Lamps On A 220-volt 
Circuit are shown in Fig. 212. As connected, only two lamps 
can be lighted at a time: With the switch closed to A', lamps 
C and E are lighted, and lamp D is extinguished; by closing 
the switch to the other side, B', lamps D and E are lighted and 
C is extinguished. By permitting the switch to remain in the 
open position both sides of the line (Li and L 2 ) are discon- 



Fig. 212. —Double-pole double-throw switch connections for operating two incandes¬ 
cent lamps in series, so arranged that only two lamps can be lighted at a time. (Switch- 
position A', lamps C and E lighted; switch-position B ', lamps D and E lighted.) 


nected from the lamp-circuit. This method of connection is 
particularly well adapted for use in industrial plants where 
restricted-selective (Sec. 17) control of 110-volt lamps on a 
220-volt motor circuit is desired. If the line, LiL 2 , is con¬ 
nected to a 110-volt supply, the lamps will—if they are 110- 
volt lamps—burn at only one-half normal voltage. The 
lamps—or lamp-groups— C, D, and E , must each be of the 
same wattage rating if they are expected to burn at normal 
candlepower when the switch is closed. 



































Sec. 202] SINGLE- AND MULTI-POLE CIRCUITS 


145 


202. Lamps May Be Connected Either In Series Or In 
Parallel By The Operation Of A Double-throw, Double-pole 
Switch as shown in Figs. 213 and 214. In Fig. 213-7 and II, 
the two lamps are in series when the switch is closed to position 
S, and in parallel when closed to P. When the switch is 




Fig. 213. —Series-parallel connections for a double-pole double-throw switch. (Lamps 
are in series when switch is closed to S, and in parallel when closed to position P.) 

open, both lamps are extinguished. The switch, when it is 
open, disconnects only one side of the line from the lamp 
circuit. In Fig. 213-/7, four conductors are required between 
the lamps and the switch, whereas in Fig. 213-7, only three are 
used. The three groups of lamps (Fig. 214) are controlled as 



Fig. 214.—Double-pole double-throw switch providing parallel and series control for 

three groups of lamps. 

follows: (1) Switch closed to A, groups C, D, and E —in parallel 
—operate at full line voltage. (3) Switch closed to B , C and 
D extinguished, and E —across the line—operates at full voltage. 
(3) Switch open, groups C, D, and E —in series—operate at 
one-third line voltage. Although such connections are 
particularly adapted to heating units, they may be employed 
10 
































































146 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 4 


in lighting where dimming is desired. The statements just 
preceding as to the voltages impressed on the lamp-groups 
assume that the total wattage rating is the same for each of the 
three lamp-groups. 

203. A Group Of Lamps May Be Controlled From Two 
Locations By Two Double-pole, Double-throw Switches 



Fig. 215.—Two-location control provided by two double-pole double-throw knife 
switches. (Neither switch should ever be left open, but always closed to one or the 
other set of jaws.) 

by arranging the connections as shown in Fig. 215. After 
the lamps have been extinguished, by means of either switch, 



Fig. 216.—Two vertically-mounted double-pole double-throw knife switches for two- 

location control. 

the switch must not be left in the open position, but must be 
closed to the opposite side. If one switch is left in the open 



Fig. 217.—Two horizontally-mounted double-pole double-throw knife switches for 

two-location control. 

position, the lamps cannot be lighted by closing the other 
switch. Figures 216 and 217 show other arrangements of the 
same circuit. 































































































































Sec. 204] SINGLE- AND MULTI-POLE CIRCUITS 


147 


204. Three-location Control May Be Obtained With Two 
Single-pole, Double-throw Switches And One Double-pole, 



Fig. 218.—Three-location control provided by knife switches. (Shunt connected 

within the switch.) 

Double-throw Switch (Figs. 218 and 219). As in Sec. 203, all 
switches must, to provide effective three-location control, 



Fig. 219.—Three-location control with knife switches (shunt or jumpers outside 

of switch). 

always after operating be left in the closed position. As 
many other locations of control as are desired may be pro- 



Fig. 220.—Control from four locations with double-pole, double-throw switches. 
(Switches A and D may, if desired, be single-pole double-throw.) 

vided by connecting (B and C, Fig. 220), for each additional 
location, a double-pole, double-throw switch into the circuit. 


































































































148 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 4 


Note.—Multi-location Control May Be Obtained By Using 
Only Double-pole, Double-throw Switches (Fig. 220). Only one 
side of the end-switches (A and D, Fig. 220) is employed, and the inter¬ 
mediate switches (B and C) are connected as shown. 

205. A Double-pole, Double-throw Switch May Be Used 
To Assist in Balancing The Load On A Three-wire-neutral 



Fig. 221. —Method of making balancing-switch connections for balancing the load on 

a three-wire-neutral system. 

System (Fig. 221). With the switch closed to position Pi, 
the branch-circuit load will be carried by conductors AB. 
By throwing the switch over to position P 2 , the load will be 
carried by BC. By thus connecting all or certain of the mains 
or branches to the feeders, the lighting load of a large building 
may be so shifted as to minimize the current which flows 
through the neutral, B. 



Fig. 222. Diagrams of connections showing two double-pole switches so arranged 
that either outside wire may be opened independently of the other, but the neutral cannot 
be opened without opening both outside wires. 

206. Two Double-pole Switches May Be Used For The 
Service Switch Of A Three-wire-neutral System. To 

comply with Code Rule 24a, Par. 5 (Sec. 137) they must be 
so connected (Fig. 222) that either outside wire, A, may be 




































































Sec. 207] SINGLE - AND MULTI-POLE CIRCUITS 


149 


opened independently of the other, and, that the neutral, B, 
cannot be opened without—at the same time—opening both 
outside wires. By opening either switch, C or D, independ¬ 
ently of the other, one outside wire is opened. When both 
switches are open, both of the outside wires, A, and also the 
neutral, B, are disconnected from the line. 


■ Double-Pole, Double-Throw Switch 



Fig. 223.—Double fuse connections for combined lighting and power circuit controlled 

by double-pole double-throw swatch. 


207. A Double-pole, Double-throw Switch Having A 
Double Fuse Connection (Fig. 223) may be effectively used 
for c.onnecting a combined lighting-and-motor circuit to the 
line. This is desirable in certain installations where the motors 
may frequently be subjected to large overloads, and where 
continuity of lighting service is of greater importance than is 
that of the motor service. When 
an accidental motor overload 
ruptures a fuse, the double-throw 
switch may be closed to the op¬ 
posite set of jaws, thus imme¬ 
diately relighting the lamps. 

The cause of the trouble may 
then be found and removed and 
the motor started; after which, 
the fuse replacement can be 

made. Fig. 224.—Schematic diagram, show- 

208. A Three-pole, Double- ing how 110-volt lamps may be con- 

, -»*■ t> tt nected through a three-pole, double- 

throw Switch IN^ay Be Used To th row switch to operate at full 
Operate 110-volt Lamps From candle-power—normal voltage—from 

Either A 110-volt Supply Or t 0 A, lamps are lighted from 110-volt 
A 220-volt Supply (Fig. 224). supply; closed to B, lamps are lighted 

. , • from 220-volt supply.) 

A switch so used is sometimes 

called a throw-over switch, or transfer switch . When the switch 
is in position A, all of the lamps are connected, in parallel, 














































150 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 4 


to the 110-volt supply, and when it is in position B, they are 
connected, in series-parallel, to the 220-volt supply. Thus 
the lamps may be operated at normal voltage from either the 


< 

<Y 




Service 

Wires 


-220 Volts : 

vL 


HO Volts 
mo Volts 

Central 
Station 
Company's 
Three-Wire 
Main In 
Street 




V////' 


'//////// ////////VVVVVVVr? 



Two-Wire 

Generator, 


-Cfr- -Q- 
-Q- -Qh \ 

Branch ‘ Lamps '' 

Three-Wire Main 
In Building...... 

. no Volts 

Branch - 


H. 


•> 


Building.. 


■ . 


::. • : . 


Fig. 225. —Schematic diagram of connections for throw-over-switch installation for 
a two-wire interior system and three-wire street mains. (Service-entrance overload- 
protective equipment and other details not shown.) 

110-volt or the 220-volt supply. In those industrial plants 
where the energy for the motors is supplied at 220 volts, and 




<• > 






'Service 

Wires 

Central 
Station 
Companys 
Two-Wire 
Main In 
Street 


l 


-no volts 


r///////////////////////////////////////////y 


-I 

— p 


Lamps -. 


Throw-Over Switch■' 
Three-Wire Generator-- 

I 

Volts 



• . —Q- 

—Q- 

' Branch---'' 

Three-Wire Main 
In Building- 


Branch. 


4 4 <!> 




Fig. 226. —Schematic diagram of connections for throw-over-switch installation for 
three-wire interior system and two-wire street mains. (Over-load-protective equipment 
and other details not shown.) 

that for lighting at 110 volts, such a transfer switch is exceed¬ 
ingly convenient for emergencies. Thus, when trouble occurs 
on the lighting circuit, the lighting load may be transferred 

































































































Sec. 209] SINGLE- AND MULTI-POLE CIRCUITS 


151 


to the motor circuit and so carried until the lighting circuit is 
repaired. 

Note. —A Throw-over Switch May Be Used In The Service To A 
Building Which May Be Fed By Either A Three-wire Or A Two- wire 
System (Figs. 225 and 226). Thus, in office buildings, energy is fre¬ 
quently generated at 110 volts, two-wire, and the street mains of the 
central-station company are 110-220 volts, three-wire, or vice versa. 
With a switch arranged as in Figs. 225 or 226, the load in the building may 
be readily shifted from one system to the other. Where either of these 
arrangements are employed, the cross-sectional area of the three-wire- 
system neutral which is within the building must be twice as great as the 
cross-sectional area of either of its outside wires. 

209. A Three-pole Double-throw Switch Arranged To 
Connect Two Lamp-groups In Either Parallel Or Series- 
parallel is shown in Fig. 227. When the lamps are, as in II, 



Fig. 227.—Three-pole double-throw switch wired to connect lamp groups in either 
parallel or series-parallel. (The arrows indicate the directions of current when the 
polarities are as shown at the left.) 


connected in parallel, then both lamp-groups, Li and L 2 , have 
impressed across them the voltage of the supply circuit, C. 
But when S is thrown to the position of 7, the lamps, now 
connected in series-parallel, have impressed across them only 
half the supply-circuit voltage—assuming that the total 
wattage of Li is the same as that of L 2 . With only half supply- 
circuit voltage across^ the lamps, their candle power is con¬ 
siderably decreased. Hence this may be used as a dimmer 




















































152 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 4 


circuit. For satisfactory operation, both of the lamp-groups 
must be of the same total wattage. 

210. The Wiring For A 120-volt Extension Lamp In A 
600-volt Parallel-series Circuit may be connected as indi¬ 
cated in Fig. 228. The stationary outlets, 1 to 5, are so 
arranged that five lamps are in series across 600 volts. One 
outlet, E, is arranged to serve the portable extension lamp. 
For each portable-extension outlet, a duplicate receptacle is 
shunted in parallel with one a stationary outlet, L, of the 
parallel-series circuit. To connect an extension lamp it is only 
necessary to plug into the extension receptacle, E, and then to 



Fig. 228.—Wiring for 120-volt extension lamp in a 600-volt parallel series circuit. 
Lamps E and L should not be “on” simultaneously any longer than necessary. 


unscrew or switch off the lamp which is in L. When the 
extension-circuit plug is to be removed from E, the dead 
lamp in L must first be screwed or switched into the circuit, 
otherwise a dangerous arc may be drawn in the receptacle. 

211. One Lamp Of A Four-lamp Fixture May Be Lighted 
From A Three-wire System as indicated in Fig. 229. The 
method shown was employed by the Kansas City Electric 
Light Company for supplying energy to the four lamps on each 
street fixture. With this method, one lamp on each fixture 
may be operated all night and still, when all of the lamps are 
lighted, the advantages of a three-wire system, is retained. 

Explanation. —At the 2,200-volt distributing board in the central 
station are a double-pole oil switch, A, (Fig. 229) and a single-pole oil 
switch, B, connected as shown. Up to midnight both of these switches, 
A and B, are closed; after that time, the single-pole switch is opened, 
thereby leaving a single night lamp on each post in service until sun¬ 
rise. Two single-phase transformers, C and D , are used for each section. 
One transformer, D, furnishes the energy for the lamps which are lighted 














Sec. 211] SINGLE - AND MULTI-POLE CIRCUITS 


153 


until midnight (with the exception of the all-night lamps); the other 
transformer, C, furnishes energy for the all-night lamps only. A wire, 
W, connects the middle points of each secondary and is grounded, in 
addition being connected to one of the lines running along the top of each 
pole. By connecting the outer wires to the transformers as shown, 
220 volts is maintained across them and the advantages of a three-wire 
system are thus obtained. The neutral wires, T, on each side of the 
street are, where practicable, “tied” together with tie wires R. 



Fig. 229.—Lighting one lamp of a four-lamp fixture from a three-wire single-phase 

system. 

QUESTIONS ON DIVISION 4 

Make a diagram of connections and explain the operation of, and the lamp control, 
which is provided by the following: 

1. Two single-pole switches connected in series. 

2. Two single-pole switches connected in parallel. 

3. Two single-pole switches controlling two groups of lamps using a common return. 

4 . Two single-pole switches connected to provide restricted-selective control for a 
single group of lamps. 

5. A single-pole, double-throw switch for dimming. 

6 . A single-pole, double-throw switch controlling two groups of lamps so that only 
one group can be lighted at a time (restricted control). 

7 . A single-pole, double-throw switch for balancing the load on a three-wire (not 

three-phase) system. 
















































154 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 4 


8. Two single-pole, double-throw switches for load-balancing on a three-phase 
system. 

9. Two-location control with two single-pole double-throw switches. 

10. Two double-pole switches connected in parallel. In series. 

11. Series-parallel connection of double-pole switches. 

12. Double-pole switch connected as single-pole. 

13. Two double-pole switches providing restricted-selective control for three groups 
of lamps. 

14. One double-pole switch for dimming to one-third normal voltage. 

15. Common errors in connecting double-pole snap switches. 

16. One double-pole, double-throw switch for: (a) Restricted-selective control. (6) 
Restricted control, (c) Restricted-selective control of . three 110-roii lamps on a 220 -volt 
circuit, (d) Series to parallel and parallel to series. 

17. Two-location control by two double-pole, double-throw switches. 

18. Three-location control by two single-pole, double-throw switches and one double¬ 
throw, double-pole switch. 

19. Multi-location control with double-throw, double-pole switches. 

20. Double-pole, double-throw switch for load balancing on a three-wire-neutral 
system. 

21. Two double-pole switches used as a service switch. 

22. Three-pole, double-throw switch for throw-over from 110-to 220-volt supply. 

23. Throw-over switch for building-service connection which will permit of either 
two-wire or three-wire operation within the building. 


DIVISION 5 


THREE- AND FOUR-WAY SWITCH CIRCUITS 

212. The Application Of Three-way And Four-way Switches 
Offers A Wide Range Of Combinations for multiple-location 
control of interior wiring lighting circuits. A single lamp or 
a group of lamps may be so arranged, in relation to two 
three-way switches, that the lamp or lamps can be lighted or 
extinguished by either of the switches independently of the 
other. If additional control locations are desired, four-way 
switches may, as will be described later, be added to the circuit 
to provide the additional control locations. The wiring con¬ 
nections and diagrams for these various switch circuits will 
be considered in the following sections. 

Note.—There Are Really Two Distinct Systems Of Connecting 
Three-way And Four-way Switches: (1) The “Standard” System 
(2) The “Carter” System; (see Fig. 283). The standard-system 
methods are first discussed and then the Carter system is described (Sec. 
249) and its advantages and disadvantages explained. 

213. Three-way And Four-way Switches May Be Utilized 
As Single-pole Switches if connected in a lighting circuit, as 




Fig. 230.—Three- and four-way switches used as single-pole switches. 

shown in Fig. 230 -I and II. These methods, of course, provide 
only one control location on the lighting circuit in which they 
are installed. While the usage of Fig. 230 is uneconomical, it 

155 









156 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 5 


may, in emergencies, be employed when single-pole switches 
are not available. 

214. Diagrams For Simple Or Elementary Three-way 
Switch Circuits For The Control Of The Circuits From Two 



Fig. 231.—Simple three-way switch circuit feeding from each end. 

Locations are shown for surface snap switches in Figs. 231, 
232, 233, and 234. Figure 234 is a phantom view showing the 
actual connections of the switches for such service, while 



Fig. 232.—Three-way switch circuit feeding from one end only. 


Figs. 231 and 232 are diagrammatic representations. From 
the connections of these two illustrations it is evident that at 
no time, either one of the switches being open, are both polari- 


/ Switch Feed Wire 



Fig. 233.—Three-way switch circuit feeding from one end, for control of several lamps. 

ties of the feeding circuit present in either switch. This 
feature renders a connection of this type strictly in compliance 
with wiring rules which are enforced in certain cities and which 





























Sec. 215] 


THREE- AND FOUR-WAY CIRCUITS 


157 


are based on Code Rule 24c. (See Secs. 144 and 251.) 
Figure 235 shows the connections where flush, push-button 
switches are used. 



Fig. 234.—Phantom diagram of a three-way switch circuit. 



Fig. 235.—Wiring diagram for three-way flush push-button switch circuit. 


215. A Three-way Switch Circuit Which Is Fed From Differ¬ 
ent Branches is outlined in Fig. 236. It will be noted that 
this connection is essentially the same as the connections of 
Figs. 231 and 234 with the exception that the feed wires 



1-2 

H 

—-i 


Fig. 236.—Three-way switch circuit feeding from two different branches. 


approach the switch-and-lamp circuit from opposite sides and 
feed from different branch circuits. In making the connec¬ 
tions of Fig. 236 it is imperative that proper care be taken to 
insure that the wires of correct polarities enter the switch-and- 













































































158 


LIGHTING CIRCUITS AND SWITCHES 


[Drv. 5 


lamp circuit from each of the branch circuits, G and H . 
Otherwise the system would be inoperative. Wherever this 
system is utilized, the switch feed and the lamp feed wires 
should each be protected by its own single-pole cutout. 

Note.—Serving A Three-way Switch Circuit From Two Differ¬ 
ent Branch Circuits As In Fig. 236 Is Not Recommended because of 
complications which may develop when trouble occurs in the circuit. 
It is, however, sometimes advisable when wiring finished buildings so that 
the taking up of extra flooring may be avoided, and for other possible 
economic reasons, to install a three-way switch circuit as shown in 
Fig. 236. 

216. The Wiring For A Three-way Switch Circuit Which 
May Be Used When The Switches Are Located Near Each 



Fig. 237.—Three-way switch circuit for switches located near each other. Only 

one polarity in either switch. 


Other is illustrated in Fig. 237. This is an adaptation of the 
“ Carter ” system of wiring which is described more in detail 
in Sec. 249. As will be notud, this provides a convenient 
arrangement in the circuit lay-out. 

217. Incorrect Three-way Switch Circuit-connections are 
sometimes made in an installation, especially where the loca¬ 
tions at which the lamp feed wire and the switch feed wire 
are tapped into the branch circuit, are spaced a considerable 
distance apart. The reason for this is that a wireman may, 
under these conditions, have difficulty in tracing out the 
branch circuit. 

Example. —Such an incorrect connection is shown in the diagram of 
Fig. 238 where C and D are both connected to wires of the same polarity. 
When a three-way switch installation is made as shown in this illustration 
it is said to be “off circuit” and, obviously, will not operate. The 
most effective way of correcting such a difficulty, especially after the 












Sec. 218] 


THREE- AND FOUR-WAY CIRCUITS 


159 


job has been completed, is to reverse the connections at the branch 
block, either at A or at B, Fig. 238. 

Note.—Three-way And Four-way Switches Are Frequently 
Mistaken For Double-pole Switches. This is because of the similar¬ 
ity in external appearance. Some of the errors in connection due to such 



Fig. 238.—Showing three-way switches with lamp- and switch-feed wires improperly 
connected to the same side (polarity) of the branch circuits. 

a mistake are shown in Fig. 239. A three-way switch connected as a 
double-pole switch (Fig. 239-7) will not light the lamp. At II, is shown 
a four-way switch connected as a double-pole switch. Lamps will be 
lighted when in position A, but when the switch is operated to position 
B, the line will be short circuited. At III, if the usual connections for a 
four-way switch are employed in an attempt to secure double-pole 
operation, the lamps cannot be turned out by the switch. 


.-Three-Way Switch .-Tour-Way Switches . _ 



I-Three-Way Switch H-Four-Way Switch Used As Double- HI-Four-Way Switch. 
Connected As Double- Pole. Line Is Short-Circuited Lamp Cannot Be 

PoleSwitch Will Hot When In Position B Turned Out 

Light The Lamp 

Fig. 239.—Common errors in the connection of three- and four-way switches. 

« 

218. A Wiring Lay-out For A Two-story-and-attic Cottage 
In Which A Three-way Switch Circuit Is Incorporated for 

the simultaneous control of both an upstairs and a downstairs 
hall light is shown in the sectional view of Fig. 240. This lay¬ 
out is probably typical of the average small-residence three- 
way switch circuit connection. 

Note.—The Switch Feed Wire On The First Story is taken from a 
“jumper” wire, J, from the single-pole switch-feed wire directly to the 
left. This construction is much more economical than that involved 










































160 LIGHTING CIRCUITS AND SWITCHES [Div. 5 



■Cutout 


Upstairs 


Second Story 


| //// cc ItOf 

J Switch- 


Single- 

Pole 

Switch- 


Downstairs ' (O 0\ 

Hall Light ... 

. single- \ 

Pole Switches’ 


-Branch Blocks 
..-Meter /C 


Single-Pole- 
Switch on 
Cel'ar Stairs 


\3-Way 
Switch 


'Cellar Light 


Basement 


Fig. 240. —Schematic diagram showing wiring in a cottage showing three-way switch 

circuit for control of hall lights. 


.--Lamp Peed Wire 



I* Section 


Switch 
Feed 
Wire--=7 


h 


FT 


Branch 
Circuit 

Lamp Feed 
Wire — n’ 

Lamp- 



Switch 

Travelers 


VT 


*• Three- 
Way 

>Switches 



Return _ 
Wire 


VJ 

jb 

£ x 
& ts 

-<- —' \ 


Lamp- 


E.-Simplified Wiring Diagram 


Fig. 241. —Lay-out and connection diagram for a residence three-way switch circuit. 











































































































































Sec. 219 ] 


THREE- AND FOUR-WAY CIRCUITS 


161 


when a special feed is run to the three-way switch. Other typical install¬ 
ations are illustrated in the sectional drawings of Figs. 241, 242, 243 and 


244. 



Fig. 242.—First and second story hall lights controlled by two three-way switches 

A and B. 

219. A Rather Unusual Case Of Three-way Switch Wiring 

is illustrated in Fig. 245. It was necessary in this building to 
so wire the hall-light circuits that they could be controlled lioni 
two locations by three-way switches and that the hall-light 
energy could be metered separately from the energy used by 
the tenants of the first and second stories. In other words, 
the owner desired to pay for the hall-lighting energy and 


li 



































































































































162 LIGHTING CIRCUITS AND SWITCHES [Div. 5 

wished each tenant to pay for the energy he used on his own 
floor. An arrangement was effected with the central station 
whereby the hall lighting was furnished at a flat rate, elimi- 



Fig. 243.—Hall-lighting three-way circuit fed from space between second and third 

stories. (Three-way switches at A and B.) 


nating the necessity of a meter for this portion of the load. This 
condition very materially simplified the problem, inasmuch 
as it was then only necessary to so connect the meter series 
coils in the branch circuits that the hall lighting current would 


























































Sec. 220] 


THREE - AND FOUR-WAY CIRCUITS 


163 


not feed through them. If the circuits of Fig. 245 are traced 
out it will be evident that the energy for the hall lights does not 
pass through any meter. 



Fig. 244.—Three-way switch circuit feeding from below. 


220. Two-location Control Of A Lighting Circuit May Be 
Effected By The Use Of Four-way Switches (as illustrated in 
Fig. 246) instead of three-way switches, if the switch travelers 
are connected to diagonal binding posts within the switches. 






































































































164 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 5 



Return 
Wire - 


Circuit for 
Second Story Flat 


Switch 
Travelers - 




Three- Way ^ 
Switch 


/ Cut-Out 


-Meter Coil 


Circuit 
for First 
-Story Flat 


First Story 


Hall 
Light---- '• 


Lamp 
Feed 
Wire - - - 


Second Story 


.-Meter Coil 


« 


Fig. 245.—Wiring for flat-rate hall lights. (Most electric lighting companies will 
not sell energy at a flat rate. Furthermore, standard practice is always to connect the 
current coil of the meter in the “hot” side. 












































Sec. 2211 


THREE- AND FOUR-WAY CIRCUITS 


165 


This illustration is self-explanatory. While the system shown 
is not to be recommended generally, because it involves a 
greater first cost than does the usual three-way switch installa¬ 
tion, it is .sometimes necessary to use four-way switches as 
shown when three-way switches are not available. 


/ Switch Feed Wire 



Fig. 246.—Two-location control of a lighting circuit using four-way switches. 


221. A Three-way Switch And A Four-way Switch May 
Be Used In Combination To Afford A Two-location Control 

of a lighting circuit. The wiring diagram for such a connec¬ 
tion is shown in Fig. 247. From a study of this it will be 
apparent that it is an adaptation of the wiring schemes shown 
in Figs. 231 and 246. 


Snitch Feed 



Fig. 247.—A three-way and a four-way switch used in combination for a two-location 

control. 


222. Single-pole Double-throw Knife Switches May Be 
Used In Combination With Either Three-way Or Four-way 
Switches to provide control of a lighting circuit from two differ¬ 
ent locations, as illustrated in Figs. 248 and 249. Neither 
of these groupings is as economical as that of Fig. 231. They 

























166 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 5 


are used for unusual conditions or in emergencies when stand¬ 
ard three-way switches are not available. 



Fig. 248. —Two-location control using one single-pole, double-throw knife switch and 

one three-way switch. 



Fig. 249. —Single-pole, double-throw knife switch used in combination with a four-way 

switch for two-location control. 

223. Pilot Or Indicating Lamps On Three-way Switch 
Circuits (Fig. 250) indicate whether the lamps in the lighting 
circuit are “on” or “off.” They are especially valuable when 
installed at three-way switch locations from which the lamps 
in the circuit are not visible. In Fig. 250 the bull's-eye 
receptacles are merely wired in parallel with the other lamps 
in the circuit. Hence, they are lighted or extinguished simul¬ 
taneously with the regular circuit lamps. 

225. Control Of A Lighting Circuit From Three Or More 
Locations May Be Effected By The Use Of Four-way Switches 
Connected In The Circuit Between The Three-way Switches, 
as illustrated in Figs. 251, 252, and 253, and 254. These show 
typical diagrams of the standard method of wiring when it is 
desirable to provide more than two control locations and are 
































Sec. 225] 


THREE- AND FOUR-WAY CIRCUITS 


167 



Fig. 250. —Pilot or indicating-lamps in three-way switch circuit. 



Fig. 251.—Three-location control utilizing two three-way switches and one four-way 

switch. 



Three - Way Switch- 


Three - Way 
Switch 


■Four-Way Switch 




To Distribution 
Cabine t - ■ 


Fig. 252.— Showing how the conductors are actually connected in the three-way and 

four-way switch for three-location control. 








































































168 LIGHTING CIRCUITS AND SWITCHES [Div. 5 

the methods which are used most frequently. Any reasonable 
number of control locations may be provided by the installa- 



Fig. 253.—A four-location control utilizing two three-way and two four-way switches. 



Fig. 254.—Another lay-out for a four-location-control circuit using three-way and four¬ 
way switches. 


tion of additional four-way switches. One additional four¬ 
way switch is required for each additional control location 
desired. 




































Sec. 2261 


THREE- AND FOUR-WAY CIRCUITS 


1G9 


226. An Installation Providing Four Control Locations, 

(Fig. 255) A, B, C, and D for the downstairs hall light, Li , 
and the upstairs light, L 2 , in a two-story residence is 
encountered frequently. These lights, L x and L 2 , can be con¬ 
trolled from both the front, A, and rear hall, D, on the first 
story as well as from the front, B , and rear, C, of the second- 
story hall. Three-way switches, A and D , provide the control 
in the first story while that in the second story is furnished by 
four-way switches, B and C, located as shown. Figure 256 



Fig. 255.—Illustrating an actual four-location control installation. 


shows a similar installation in which three second-story hall 
lights, Li, L 2 , and L 3 , and a first-story hall light, L 4 , are con¬ 
trolled from three locations which are: First story, 0, second- 
story rear hall, N, and second-story front hall, M. 

227. Four-way Switches May Be Used Without Three-way 
Switches To Provide Control Of A Lighting Circuit From 
Three Or More Locations by following the directions dia¬ 
grammed in Fig. 257. Obviously, this method is more expen¬ 
sive than one for which three-way switches are used (instead 
of the four-way switches) at A and B. However, it is some- 
























































































































170 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 5 


times necessary to thus use four-way switches when the three- 
way switches cannot be obtained. 



Fig. 256.—Four hall lights, L\, Li, Li and Li, controlled from three locations. 



Fig. 257.—Three-location control using three four-way switches. 


228. A Three-location Control May be Provided By Arrang¬ 
ing Two Four-way Switches In Combination With A Single¬ 
pole, Double-throw Knife Switch wired as diagrammed in. 
Fig. 258. This method of wiring is also more expensive than 
if the control were effected by the use of two standard three- 
way and one standard four-way switch. It illustrates an 





























































































































































































































Sec. 229] 


THREE- AND FOUR-WAY CIRCUITS 


171 


improvisation which may be employed in special cases or in 
an emergency. 



Fig. 258. Three-location control; two four-way snap switches and one single-pole 

double-throw knife switch. 



Fig. 259.—Two three-way snap switches and one double-pole double-throw knife 

switch for three-location control. 



Fig. 260.—Three-location control using two four-way snap switches and one double¬ 
pole double-throw knife switch. 

229. A Double-pole, Double-throw Knife Switch May Be 
Used To Provide A Third Control Location when installed in 
combination with either two three-way switches or two four¬ 
way switches, as portrayed in Figs. 259 and 260, respectively. 



































































172 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 5 


The reversing of the polarities of the switch travelers at the 
third control location, D, in Figs. 259 and 260 is accomplished 
by placing jumpers diagonally across the contact jaws on the 
double-throw switches, as shown in the illustrations. 

230. A Four-location Control Utilizing A Single-pole 
Double-throw Knife Switch, A, A Double-pole, Double-throw 


. ,-Branch Circuit 

*■ ■•Aft? .---Single - Pole, Double-Throw 

Knife Switch ...switch Travelers ...... 

■y _±1 

Switch 
Feed 
Wire 



Three - Wau 
Switch 



Double -Pole, Double--Throw 
Knife Switch 


Lamp Feed Wire-'" 


-Lamps--’’ 


Fig. 261.—Combination of knife and snap switches for three- and four-way switch 

circuits. 


Knife Switch, B, A Four-way Switch, C, and A Three-way 
Switch, D is illustrated in the diagram of Fig. 261. It will 
be noted that the polarity-reversing arrangement on the 
double-pole double-throw switch, B, is provided by jumpers 
bridging diagonally between the contact jaws as in Fig. 219. 



Fig. 262.—Another combination of switches for a four-location control. 


This diagram demonstrates the latitude which is obtainable 
in the multi-location control of lighting circuits by using 
switches of different types. Another example of an installa¬ 
tion, involving four different control locations, in which 
switches of a variety of types are used, is that presented in 





































































Sec. 231] 


THREE- AND FOUR-WAY CIRCUITS 


173 


l^ig. 262. For multi-location control using knife switches 
only, see Div. 4. 

231. A Restricted-control Switch Circuit For Hall Lights 

which provides an economical arrangement, when it is not 
desired at all times to have the hall-way brightly illuminated, 
is shown in Fig. 263. Three three-way switches, A, B± and 
B 2 , are installed. Switch A is located on the second floor 
while switches Bi and B 2 are located in gang on the first floor. 
The 10-watt and the 60-watt lamps at C are both mounted in 
the same fixture and tapped by the lamp feed wire at C. 



Explanation. —If the circuit diagram is traced out it will be found that 
only one of these lamps can be lighted at any time and that the position 
of the contacts in switch B 2 determines which of the lamps will be cut 
in service. It will further be noted that neither of the lamps can be 
extinguished from switch B 2 without lighting the other, and vice versa. 
Either switch A or Bi will, however, turn off whichever light happens to 
be burning and will, of course, turn it on again. But, if the 10-watt lamp 
is burning and it is desired to extinguish it and light the 60-watt lamp, 
this can be done only from switch B 2 . 

232. Another Restricted-control System For Hall-way Or 
Show-window Lights (Fig. 264) may be assembled by using a 
single-pole, S, a three-way, T , and a four-way, F, switch in 
combination. These connections afford about the same 
selection in lamp control as does an electrolier switch (Div. 7). 

Explanation. —The single-pole switch, S (Fig. 264) controls the 
entire circuit. That is, if switch S is turned off, the lamp B and the lamp 
group A cannot be lighted at switches T and F. However, if switch S is 
in the “on” position, it is possible, as will be revealed by a consideration 
of the diagram, to control group A or lamp B from either the three-way 



















174 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 5 


switch T or the four-way switch F. But at no time can group A and 
lamp B be lighted simultaneously. That is, when group A is lighted B is 
extinguished and when B is lighted group A is extinguished. It will be 
further noted from this diagram that both lamp B and group A cannot 
be extinguished simultaneously from either switch T or switch F. 



233. A Restricted Control Three-way Switch Circuit For 
Up-stairs And Down-stairs Hall Lamps is shown in Fig. 265. 

The arrangement, as illustrated, is for a three-lamp 
fixture, L 2 and L 3 , located in the lower hall and a single 
lamp, Li, located in the upper hall. The two three-way switches, 



Fig. 265.—Two-location restricted control employing three three-way switches. 

B and C, which are mounted in gang, are located near the entrance 
to the lower hall. Switch A is located in the upper hall. 
Lamp Li and L 2 comprise one lamp-group—although one is up¬ 
stairs and the other down-stairs. Lamps L 3 comprise the second 
lamp-group. Only one lamp-group—either LiL 2 , or L 3 —can 
be lighted at one time, Either group may be extinguished or 


































Sec. 234] 


THREE- AND FOUR-WAY CIRCUITS 


175 


lighted by either A or B, but the lamp-group which is so lighted 
or extinguished by A or B will be determined by the position 
of C. 

Explanation. —If a person, upon entering the lower hall wishes .to 
light the lamps, he operates B. This will light one lamp-group—either 
LiL 2 , or L 3 —and the lamp-group which is so lighted is determined by the 
position of C. If upon operating B, the lamp-group which lights is the 
one that is not wanted, the other lamp group may be lighted by operating 
C. If a person is in the upper hall and operates A, one of the lamp- 
groups will be lighted; if it is the wrong one, he must go down-stairs and 
operate C, whereupon the other lamp-group will be lighted. One of the 
lamp-groups—depending upon the position of C —may be lighted and 
extinguished by either A or B. 

234. A Three-way Switch Circuit Providing Restricted 
Control From Either Of Two Locations is shown in Figs. 266 



Fig. 266.—Restricted control of up-stairs and down-stairs hall-lamps from two locations. 

See Fig. 266A for installation lay out. 

and 266A. The three-way switches, A and B, which are mount¬ 
ed in gang, and lamp L 3 may be located in the up-stairs hall¬ 
way. Switches C and D, which are similarly mounted, and 
lamps L 4 and L 5 may be located in the lower hallway. Lamp L 3 
and L 4 comprise one lamp-group, and lamps L 5 comprise an¬ 
other lamp-group. Only one lamp-group—L 3 andL 4 , orL 5 —can 
be lighted at any one time. The lamp-group which it is desired 
to light is selected by either switch B or D. The lamp-group 
so selected may be lighted or extinguished by either A or C. 

Explanation. —A person entering the lower hallway at night, when 
all lamps are out, operates switch C. This will light one of the lamp- 



























176 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 5 


groups. The lamp-group—L 3 L 4 , or ^6—which is lighted thereby, will 
depend upon the positions of B and D. If the lamp-group which happens 
to light, upon operating C, is the one which is not wanted, switch D is 
then operated. The same results may be obtained from the upper hall¬ 
way by operating switches A and B. 



235. A Combined Restricted And Selective Four-way 
Switch Circuit For Hallways Or Show Windows is shown in 
Fig. 267. With switch A open, restricted control (Sec. 15) is 
provided since only one lamp can be lighted at a time. 



Fig. 267.—A combined restricted and selective circuit. (When A is open the control is 
restricted; when A is closed the control is selective.) 

Explanation. —That is, if A is open, B' may be lighted by operating 
B. Then before the operation of C will light C', B must be operated 
















































































































































Sec. 236] 


THREE- AND FOUR-WAY CIRCUITS 


177 


to extinguish B'. And before D can be operated to light D', both B and 
C must be placed so that both B' and C are extinguished. With switch 
A closed, all three of the lamps, B\ C', and Z)', will be lighted regardless 
of the positions of B, C, or D. 

Note. A Three-way Switch Circuit Providing Restricted 
Control Which Is Intended To Minimize Current Consumption is 
shown in Fig. 268. Such an arrangement is well adapted for guest-rooms. 
Only one lamp-group can be lighted at any one time. 



Fig. 268.—Restricted control of lamps provided by three-way switches. (Only one 
lamp or group of lamps can be lighted at a time.) 

236. An Example Of The Simultaneous Control Of Three 
Hall Lamps from any of three locations, A, B, and C, is shown 
in Fig. 269. This arrangement of switch control is, in gen¬ 
eral, similar to that diagrammed in Fig. 256 and is merely a 
modification, to satisfy a given set of conditions, of a typical 
three-way-four-way switch circuit. 

237. A Stairway Lighting Circuit Wherein Restricted 
Selective Control Is Effected by the use of three-way, single¬ 
pole and double-pole switches is illustrated in Fig. 270. The 
object of this installation is to provide a system whereby one 
can illuminate the stair landing at which he happens to be as well 
as the one either above or below him as he goes up or comes 
down the stairs. The switch at each landing is operated in 
passing. 

Explanation. —Assume that the two single-pole switches (Fig. 270) 
on the fifth floor are in the “on” position and that the three-way switches 
on the fourth, third and second floors are in the positions indicated, and 
that the double-pole switch on the first floor is in the “off” position. 
Now, it is obvious that if a person on entering the building, will throw the 
double-pole switch at the first-floor stair landing he will light the hall 
lamp on the first floor as well as the hall lamp on the second floor. He 
mounts the stair and when he reaches the second-floor landing operates 
12 
























178 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 5 



Fig. 269.—Simultaneous control of lamps from three locations. 











































































Sec. 237] 


THREE- AND FOUR-WAY CIRCUITS 


179 


the three-way switch there so that the contact is reversed from that shown 
by the illustration. This, as will be evident from a study of the diagram, 
lights the hall lamp on the third floor and at the same time extinguishes 
the first-floor lamp. The second-floor hall lamp remains lighted. Now, 
he mounts to the third floor and reverses the contact of the three-way 
switch there which extinguishes the lamp on the second floor and at the 
same time lights the one on the 
fourth floor. Upon reaching the 
fourth floor he reverses the contact 
of the three-way switch at the stair 
landing there which extinguishes 
the third-floor lamp, at the same 
time lighting the fifth-floor lamp. 

Both the fourth-floor lamp and the 
filth-floor lamp can be extinguished 
by the single-pole switches shown 
at the fifth-floor landings. 

Coming down the stairway (all 
of the three-way switch connections 
having just been reversed from 
those shown in Fig. 1, if it is de¬ 
sired to illuminate the fifth-floor 
hall lamp and the fourth-floor hall 
lamp the two single-pole switches at 
the fifth floor are both thrown to 
the “on” position. Now, having- 
descended to the fourth floor hall 
he operates the three-way switch 
there which extinguishes the fifth- 
floor hall lamp and lights the 
third-floor hall lamp; the fourth- 
floor lamp remaining lighted. 

Descending to the third floor the 
three-way switch at the stair Fig. 270.—For control of stairway lights 

landing there is operated, which dis- “ a P er9on gocs up or down ' 

connects the fourth-floor hall lamp 

and lights the second-floor hall lamp, the third-floor lamp remaining 
lighted. Now after descending to the second floor, the three-way switch 
there is operated which disconnects the hall lamp on the third floor and 
connects the one on the first floor, the second-floor hall lamp meanwhile 
remaining connected. Then having reached the first-floor stair landing 
the double-pole switch there is thrown to the “off” position and this 
operation extinguishes both the first and second-floor hall lamps. 

From the foregoing it will be evident that the switches on the second, 
third, fourth, and fifth floors are now in the position in which they 
originally were and that the lamps on these floors may be successively 
lighted as first described. Discretion must be used in applying this circuit 



















































































180 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 5 


because for successful operation the switches must be manipulated exactly 
in the sequence outlined. If some person other than the one who is 
mounting or descending the stairs steps out on one of the floors and turns 
a switch, the control will be disorganized. When a misconnection is thus 
effected considerable difficulty may be encountered in locating the 
trouble. 

238. Another Three-way Switch Circuit For The Control 
Of Hallway Or Stairway Circuits is diagrammed in Fig. 271. 
An installation, when arranged according to this scheme per¬ 
mits any lamp to be lighted or extinguished, independently of 



Fig. 271.—Three-way switch-circuit for hallway or stairway lamps. 

any other lamp, from each of two locations. Such an arrange¬ 
ment is particularly adapted for stairway lighting, and for 
lighting a series of hallways which are at right-angles with 
respect to each other. Whether for hallway or stairway 
lighting, the switches A and F should be located, respectively, 
at the entrance and the exit of the passageway. The inter¬ 
mediate gang switches, BC and DE, should be installed at or 
near a turn. The lamps, should be located one between each 
switch location about midway of a straight run of the hall or 
stair. 

Explanation. A person, upon entering the passageway operates 
switch A to light lamp G. This lamp, which is located between A 
and BC, then lights the way to BC. At BC, lamp G may be extinguished 
by switch B and lamp H lighted by C, whereupon the person may pro¬ 
ceed along a lighted pathway between BC and DE. If at DE, say, the 
person wishes to enter a room and leave the passageway unlighted, 
H may be extinguished by D. If there are doors along the side of 
any of the hallways at which a control for the lamp in that hallway 
















































Sec. 239] 


THREE- AND FOUR-WAY CIRCUITS 


181 


is desired, such control locations may be provided by connecting four¬ 
way switches into the travelers (see Fig. 251) and installing the switch 
at the desired place. Note that a person may enter the passageway; 
proceed in either direction, and have a lamp always lighted in front of 
him, and extinguish the lamps behind him. The principal objection to 
this arrangement is the large amount of wire which is required (see Sec. 
254 and Fig. 292). 

239. A Practical Installation Of Three-way Switches For 
Storerooms And Warehouses, is that in the installation shown 


14 Circuit 



Three-Way 

Switches 


Duplex 
Receptacle 
Outlet 


Lamp 

-Outlets 


Stock Shelves .. 


Cutout Cabinet 


Switch Outlet 10Amp. 
Single-Pole Push¬ 
button Switch 


''-Drop Cord Outlet With Key Socket 7-o"From rtoor On Circuit No- 3 
Drop Cord Outlet With Keyless Socket 7-0"From Floor On Circuit No. 4 
Switch Outlet 10-Amp. 3-Way Push-button Switch 


- —i— = 1 Wire In Conduit 
Short Cross Lines Indicate —«— -2. Wires In Conduit 

Number Of Wires In Conduit, Thus —«—= j Wires In Conduit 

.—hi—= 4 Wires In Conduit 


Fig. 272.—Wiring diagram showing conduit installation of three-way switches in 
second-floor stockroom of Cluett-Peabody Company, Chicago. L. H. Lamont & Co., 
Contractors. 


in”Fig. 272. The problem was one of providing adequate 
lighting for the numerous bins and stock shelves of this room, 
in which is kept a large stock of men’s wear, and at the same 
time keeping the electric-energy consumption as low as 
possible. It was very desirable not to have the lighting 
arrangement interfere with the efficiency of the workmen. 
The nature of this stock is such that the orders invariably 
consist of a wide variety of different articles in small quan- 

























































































































































































182 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 5 


tities. The individual orders are usually gathered by one 
man from the different shelves and taken to the wrapping 
table (not shown) which is situated in the upper right corner 
of the room. Three-way switches were used as indicated to 
effect the desired control. 

Explanation. —If key sockets alone were used a man who is ‘‘gather¬ 
ing” an order, in order to turn on the light, would have to drop whatever 
stock he was carrying at the time, turn on the light, pick whatever stock 
was needed, turn off the light and grope his way out in the dark, or the 
light would have to be kept burning. As it often happens that the stock 
from certain sections is needed but once or twice during the day, this latter 
method would not be desirable as it would entail an unnecessary waste of 
energy. As the workmen have adopted a progressive system of gather¬ 
ing the stock, by which they start from one point and fill the various 
items as they go along, single-pole switches could not be used to advantage 
as they would necessitate going back to the point where the switch 
was located. 

This problem was practically solved by the installation of 88 three-way 
switches, one at each end of each tier of stock shelves. As is evident 
from the diagram the gatherer can with this arrangement, start from any 
point, turn on the lights in any tier by means of the three-way switch 
located near the entrance, pick the stock required from that tier and, 
on leaving the tier at the other end, turn the lights off. Although 
slightly more expensive than a similar installation using single-pole 
switches or key sockets, the saving in energy-consumption is expected, 
in a short time, to offset this additional cost. (Electrical Review, 
Feb. 15, 1919.) 

240. A Garage Three-way Switch Circuit Wiring Diagram 

is illustrated in Fig. 273. In this illustration the three-way 
switch, A, is located within the owner’s house while three- 
way switch B is located within the garage. This arrangement 
renders it possible to light or extinguish the garage lamp, L, 
from both switches, A and B. If it is desired to install an 
electric heater on this same circuit so that it will operate on its 
own switch, independently of three-way switches A and B , 
the wiring for such an extension may be installed as 
diagrammed in Fig. 273-/7, which will, as shown, necessitate 
an extra run of wire from three-way switch A to heater 
switch S. 

Note.—If The Garage Three-way-circuit System Is Laid Out In 
Accordance With The Carter System (Sec. 249) the diagram will 


Sec. 241J 


THREE- AND FOUR-WAY CIRCUITS 


183 


then be as shown at Fig. 273-///. With the Carter system, an extension 
for a heater circuit operating independently of three-way switches A and 
B may be installed as shown in IV. A saving in wire is thus effected, as 
is evident from a comparison of the diagrams of II and IV. 


^ eeo ^ -' Residence 

,'Wire y 


Thr?e - Way 


/ Return Wire 



I” Standard Three-Way Switch Circuit Diagram 

(Switch Feed Wire , , Three-Way 



ah-Residence 


yZ Heater Feed Wire 


Switch -_ 


1C 


Switch Travelers'A 


v. Three-Way 
'Switch 


Lamp Feed Wire A 


Oarage - - - >- 



IL - Standard Three-Way Switch Circuit Diagram with Heater Extension Circuit 

Li _ _ (Return Wire 

- - Three - Way Threie - Way 


EZZ 


Line A, 
Wires 




Id 


Switch 


Switch 


<--Residence 


Oarage 




m - ‘Carter ,, SystemThree-Way Switch Diagram 

zz?1 ... _ . Three-Way-.. 

Switch 


-Three-Way Switch 


> Heater Feed Wire 


A ‘ -Residence 


Oarage - - > 



K"‘Carter” System Three-Way Switch Circuit Diagram with Heater Extension Circuit Heater ' 


Fig. 273.—Standard and Carter system three-way switch circuits for the control of 
garage lights. (This illustrates the economy in wire which, under certain conditions 
results from the application of the Carter System.) 


241. The Wiring Diagram For A Remote-control Vacuum 
Cleaner Motor Installation, ^ to 2 hp., which is served by an 
alternating-current single-phase line, is illustrated in Fig. 274. 
The connections on the basement panel board are not shown 
in this diagram. But the switch feed wire, after passing- 
through the main fuse and knife switch at the left of the board, 
enters the magnetic switch, passes through it, thence through 
the three-way, four-way and three-way switch combination 
and thence to the motor. The other line wire serves the 
motor direct. The installation of a magnetic switch is not 
justified for the smaller motors. For these, the switch feed 
wire, after passing through the main fuse and switch, enters 






































































184 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 5 


the three-way, four-way and three-way switch combination 
and thence is carried directly to the motor, as is obvious from 
a study of this diagram. The remote or independent control 
of the vacuum-cleaner motor is accomplished at the first, 
second, third, and fourth floors, as shown, in a manner similar 
to that described in Sec. 225 and diagrammed in Fig. 253. 


* 10-Amp. Double ■Pole Switches 



Fig. -274.—Remote control of vacuum Fig. 275.—Control of vacuum-cleaner motor 
cleaner motor using three- and four-way with double-pole switches, 

switches. 


Note.—In Making An Installation Which Is Based On The Use 
Of An Arco Wand Cleaner, one of the three-way switches (A, Fig. 
274) should be located at a point not to exceed 4 ft. distant from the 
cleaner relief valve so that both may be readily reached simultaneously. 
The reason for this is that, when cleaning the gauze sieve in the relief 
valve of an Arco cleaner, the operator must be able to throw on the 
switch controlling the motor and at the same time manipulate the 
relief valve. If the switch A were located out of reach of the relief valve, 
then it would be necessary for a person cleaning the gauze sieve to have an 
assistant turn the switch A on and off. 























































































































Sec. 242] THREE- AND FOUR-WAY CIRCUITS 185 

242. A Vacuum-cleaner Wiring Diagram for And %-hp. 
Motors which provides independent control at five stations, is 
illustrated in Fig. 275. A study of this circuit will render 
obvious the sequence of operation. The double-pole switches, 
which are used on each of the floors, work independently of 
each other. That is, if the first-story switch is turned to the 
“on” position, the operation of the motor can be stopped only 
by turning this same switch to the “off” position. It cannot 
be controlled from any of the other switches at either the 
second, third, fourth, or fifth stories (see Sec. 241). 

243. The Determination Of Three-way-switch-circuit Con¬ 
ductors, that is, the identification of the proper wires at the 
switch outlets, before connection to the switches, is sometimes 



Fig. 276.—Conductors of a three-way switch circuit as they appear at the outlets 

before connection to the switches. 

confusing to the wireman. There are (Fig. 276) always three 
wires at each of the two three-way switch outlets. One pair 
of wires AiA 2 and BiB 2 at each outlet extends, in the standard 
connections (Sec. 249) between switches, as shown in preced¬ 
ing illustrations and in Fig. 276; these wires are designated as 
11 switch travelers ” (Sec. 14). The third wire, P F h from one of 
the switch outlets is connected to one (for example, the posi¬ 
tive) side of the branch feeding the three-way circuit and is 
designated the switch feed wire. The third wire, F 2 C 2 , at 
the other switch outlet returns to the lamps; this wire is 
termed the return wire. The wire CiN which connects the 
lamps to the other side of the circuit is called the lampfeed 
wire. The switchfeed and the return wire at each three- 
way switch outlet should be marked for identification, prior 
to “testing out and connecting up” for service. This may be 
done by twisting them together, knotting them, nicking the 


















186 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 5 


insulation or baring (“skinning”) their ends. If the ends of 
the wires are thus bared for identification this will save time 
when the wireman tests out. It is unnecessary to mark 
either of the traveler wires for identification against one another 
as it is immaterial in what position, relative to one another 
they are connected. 

Note.— A Method of Testing A Three-way Switch Circuit Which 
Has Been Installed as in Fig. 276 wherein the switchfeed, PF i, and 
the return wire, F 2 C 2 , at each switch outlet have been previously marked 
for identification, follows. This ‘‘testing out” is to insure that 
the wires have been properly identified and connected. The cir¬ 
cuit may be tested either with a bell-and-battery set or with a magneto, 



Fig. 277.—Testing complete three-way circuit for continuity. 


as in Fig. 277. While in this illustration the magneto is, for convenience, 
shown connected to the branch circuit wires, it is usual to “ring out” the 
circuit direct from the distribution center where the wires are tapped 
to the branch blocks. The object in “ringing out” a circuit, the wires of 
which have been properly identified as previously described, is merely to 
ascertain whether all of the wire runs are continuous and whether or not 
the connections to the branch circuit have been properly made. To do this 
it is only necessary to short-circuit wire ends (Fig. 277) F 1 A 1 B 1 , F 2 A 2 -B 2 , 
and CiC 2 . Then ring out the circuit. If the magneto rings when 
operated, the circuit is in all probability continuous and properly con¬ 
nected. However, if it is impossible to “get a ring” from the magneto 
there are two possible causes of the difficulty: (1) The connections are 
“off circuit ,” that is, both of the feed wires to the circuit are connected 
to the same branch wire. (2) There is a break or open in one or in several 
of the component conductors of the three-way circuit. 

244. If It Is Necessary To Ascertain Which Are The Switch 
Feed, Which The Return Wires And Which The Switch 
Travelers in the event that the switch feed and return wires 






















Sec. 245J 


THREE- AND FOUR-WAY CIRCUITS 


187 


have not been properly marked for identification when 
installed, this may be done (Fig. 278) by ringing out and isolat¬ 
ing traveler wires AiA 2 and BiB 2 . The third remaining wire 
at each of the outlets will, of course, be the switch feed and 
return wire respectively. Sometimes the switch outlets are 
too far apart to permit of the ringing out the traveler wires 
AxA 2 and B X B 2 , in this manner. In such cases (Fig. 276), 
short circuit, that is connect together, wires FiAiBi and test 
successively, with the magneto, across any two of the three 
wires, F 2 A 2 B 2 at the distant three-way switch outlet until 



F " T ’ 7 T y 7%r Three-Wau Switch' 


Three-Way]: 
'Switch Outlet. 


Switch'. 
'■Feed:. 
• Wire v 


Switch Travelers 


Lamp Feed. 
['■■Wire FT-:/ 


Return Wire 


Lamp Outlet': - - V.- 


-^--Magneto 


Fig. 278.—Testing to identify the travelers. 


the magneto rings. The two wires on which the magneto 
rings will be the travelers. Now, connect together these two 
traveler-wire ends and test successively, with the magneto, 
across any two of the three wires at the first switch outlet, 
FiAi and B i until the magneto rings. This will identify the 
travelers at the first outlet. 

Note.—While Making This Test, wires C i and C 2 at the lamp 
outlet should not be connected together. When the travelers have been 
identified at one outlet as at A, Fig. 279, they can be connected together 
there as shown and tested out at the other outlet with a bell-and-battery 
set. This method of isolating the traveler wires is essentially the same as 
that just described but shows the test as being conducted with a bell- 
and-battery outfit. 

245. To Ring Out The Feed Wires connect wires C i and C 2 
at the lamp outlet, Fig. 276, and (after short-circuiting the 
branch wires at the distribution cabinet) connect the magneto 





















188 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 5 


to wires F 1 and F 2 . If the connections at the branch are 
correct the magneto will ring. If the magneto rings when the 
branch wires are not connected together it is probable that the 



Fig. 279.—Method of testing out a three-way switch circuit with an electric bell. 


switch-feed wire and lamp-feed wire connect to the same 
side of the branch circuit. The remedy for such trouble is 
obvious. 























































Sec. 246] THREE- AND FOUR-WAY CIRCUITS 189 

246. Testing Out A Three-way Switch Circuit Installed In 
A Conduit System is illustrated in Fig. 280. This test may be 


Switch 
Outlet 
Box --- =7 ' 


Switch .. 
Outlet '\- 
Box 


■Travelers 




'S' — Conduit--- - ^ 


m 


Switch 
Feed Wire 




'-Lamp . 


Return 

Wire 


Switch--,-A 
-Travelers 



I- Conductors JH-Conductors H-Completed 

In Original Position Tested and Connected Connections 


TZ- Circuit 
Diagram 


Fig. 280.—Identifying conductors in a three-way switch circuit in conduit. 


conducted with either a magneto or with the bell-and-battery 
outfit previously described (Sec. 244). The diagram of Fig*. 
280 may, at first, seem much more complicated than those of 







































































































190 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 5 


Figs. 276, 277, 278 and 279. But this is due to the fact that 
in the conduit system shown all of the wires in the circuit are 
carried within the same conduit run. The manner of isolating 
the feed and the return wires is exactly the same as that 
explained in conjunction with Figs. 276 to 279, inclusive. In a 
conduit installation like that of Fig. 280, it is an excellent plan 



'.Three-Way Switch Outlet. 
Tro/veters TO : 

l-four-Way Switch .Outlet ; 


■ Three-Way Switch Outlet. 


Travelers 


Return 


Wire 


Switch 


Feed 


Wire 


TThree-Way, Four Way Switch Outlet's After Roughing In 


Travelers 



IL-lsola+ing Travelers At Three-Way Switch Outlets 



Return 

Wire- t 

v 


Four-Way Switch Outlet 


7^ >- r Three-Way Switch Outlet. : Travelers '• ; T, : 

f-v Travelers'. fTf •’/(/•.; ' ’ Travelers-’- 

'' Three-Way Switch Outlet-'" 

Magneto---> ~ 


V 

Switch ■: 
Feed ! 
Wire- 1 


HHsola+inoj Travelers At Four-Way Switch Outlet 



KrCompleted Connections 


I 1 ig. 281. Identifying the conductors of a three-location control circuit. 


to use duplex wire for the switch travelers and a single-conduc¬ 
tor wire for the switch feed and the return wires. The use 
of conductors of these types will eliminate the necessity of 
testing out the circuit, after its installation, to determine the 
identity of the various wires. 

247. To Test Out A Three-way, Four-way Switch Circuit 

(Fig. 281) first identify the switch feed wire to one three-wav 




















































































Sec. 2471 


THREE- AND FOUR-WAY CIRCUITS 


191 


switch and the return wire from the other three-way switch. 
This may best be done, as shown at II, by twisting together the 
bared ends of the four wires (at the four-way switch outlet, F) 
which form the two sets of travelers between the four-way 
switch and the two three-way switches. Then ring out the 
wires at each of the three-way switch outlets, as shown at II, 



I* Carter”System Arranged For Two-Location Control 
( Using Four-Way Switches) 



I-Carter” System Arranged For Three-Location Control 
(.Using Four-Way Switches) 




■Three-Way 

Switch 


Three-Way Switch 


Lamps-'-' 



Four- Way Switch - • 

- rf 

d 


M 


A - Double -Pole, Double-Throw, 
Knife, Master Switch 




HI- Carter” System For Three-Location Control With 
Master Switch At Fourth Location 


A^p-Three- Way 

.-Incandescent Lamps -.,, 

(CSwitch 

LVU' Ml 

^ ^ (flf 



£ --Three-Way 
Switch 


W-Carter”System For Two-Location Control 
( Using Three-Way Switches) 



~%r Carter” System For Three-Location Control 
( Using Two Three-Way Switches And One Four-Way Switch ) 

Fig. 282. —Showing wiring diagrams of the so-called “Carter” system. 


until the two traveler wires are found the other ends of which 
have been short-circuited by being twisted together at the 
four-way switch outlet F. The remaining wire, at each of the 
three-way switch outlets, is the switch-feed wire in one case 
and the return wire in the other. These switch-feed and 
return wires should each be marked by knotting, baring their 
ends, notching the insulation, or otherwise. 














































192 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 5 


248. The Other Two Wires At Each Of The Three-way 
Switch Outlets, T\ and T 2 (in Fig. 281, III) which form the 
travelers to the four-way switch should now have their bared 
ends twisted together, as shown. The bared ends of the four 
wires in the four-way switch outlet are untwisted and each is 
rung out with the other until it is found which of the wires 
pair with one another. The two sets of travelers having thus 
been identified and paired, they are now connected to the four¬ 
way switch binding posts, as shown in the illustration of IV. 
The two travelers and the return wire are connected in one 
three-way switch as shown at the left of IV, while the switch 
feed wire and the two travelers are connected to the other 
three-way switch as shown to the right of IV. 

249. The So-called “Carter” System Of Multi-location 
Lighting-circuit Control (Fig. 282) is one wherein two or more 




Fig. 283.—Diagrammatic definitions of the “Standard” and the “Carter” systems of 

wiring three-way switch circuits. 

three- or four-way switches (A and C, Fig. 282) is connected 
to both sides of the line. Various Carter-system circuits and 
connections, and also the advantages and disadvantages of 
this system are discussed in the following sections. 

Note.—The Usual Method Of Wiring Three- And Four-way 
Switch Circuits, which has been described in preceding sections is 
herein called the standard system (see Fig. 283) to distinguish it from the 
Carter system. 
























Sec. 250J 


THREE- AND FOUR-WAY CIRCUITS 


193 


250. The Carter System Is Often Employed To Effect A 
Wire-saving (Fig. 284). The location of the lamps and 
switches shown in Fig. 284 is an exact replica of that in Fig. 
255. However, in Fig. 284, the Carter system of wiring is 



Fig. 284.—Illustrating an actual four-location control installation using Carter system. 

used, whereas in Fig. 255, the wiring is the standard (Sec. 249) 
method. By scaling the length of wire which is used in each 
installation (Figs. 255 and 284), it will be found that approxi¬ 
mately twice as much wire is required for the installation of 



Fig. 285.—Simple “Carter” system two-location control circuit. 


Fig. 255 as for that of Fig. 284. Since with the Carter system, 
it is possible to connect additional lamps (M and N, Fig. 285) 
in the branch circuit beyond the furthest three- or four-way 
switch, an additional wire-saving, which is not shown by Fig. 

13 











































































































































194 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 5 


284, may frequently be effected by utilizing this same branch 
circuit for lamps which are located in other rooms. These 
lamps (M and N, Fig. 285) are entirely independent of those, 
J, controlled by the three-way switches, that is, they can 
not be lighted or extinguished by the three-way switches. 

251. The Carter System Of Wiring Is, In Some Cities, 
Prohibited By Ordinance. This is probably because of the 
fact that the first three- and four-way switches which were 
marketed did not possess a positive and quick “snap action, ” 
but were slow and “draggy” in breaking the circuit. Both 
sides of the line are (Sec. 249), in the Carter system, connected 
to each of the “end-switches.” Hence, this slow-break me¬ 
chanism of the pioneer three- and four-way switches frequently, 
during operation, short-circuited the line. However, a 
properly-constructed three- or four-way snap switch, when 
both sides of the line are connected to it, will, probably, present 
no greater fire hazard than will a double-pole snap switch 
when both sides of the line are connected to it. 

Note.—The Carter System Of Connection For Three- And 
Four-way Switches Is Not Contrary To 1920-Code Requirements in 
spite of the fact that it was formerly, in most quarters, held to constitute 
a Code violation. It is obvious that if a single-pole switch is connected 
to both sides of the line, a short-circuit will result upon closing the 
switch. This fact, together with an erroneous interpretation of Code 
Rule 24c, Par. 3, (see Sec. 144) to the effect that three-way switches are, in 
every respect , to be considered as single-pole switches, has led many 
inspectors to prohibit the Carter connections. However, three-way 
switches are properly considered as single-pole switches (Rule 24c, 
Par. 3), only insofar as the requirements of Rule 24c, Par. 1 (see Secs. 141 
and 142) are concerned. 

Note.—It Is Very Likely That The 1923-Code Will Contain The 
Following Three-way-switch Rule (see note under Sec. 118): 
“Three-way switches are considered as single-pole switches and shall be 
so wired that only one (l).pole of the circuit will be carried to either 
switch.” If this rule is incorporated in the 1923-Code, the “Carter” 
system of connecting three- and four-way switches as described herein 
will be a violation of Code requirements. 

252. Some Of The Switch Combinations Which May Be 
Used In The Carter System are shown in Figs. 286, 287, 288 
and 289. Figure 286 shows three-way snap switches used for 
two-location control wired in accordance with the “Carter” 


Sec. 252] 


THREE- AND FOUR-WAY CIRCUITS 


195 


system. In Figs. 287 and 288 are shown respectively three- 
way and four-way snap switch combinations and three-way 


'T-. 


- Three ■ Way Switches - 

.■Lamp Feed Wires -, 


.-T 


W 



' »r/-r- - --- W///A - - -:-VvO \ 

—As -' Switch -4Zjr^~-Lamp ■' \. 

y -d 

/ 



Feed Wires : 

Lamp 


• 

P -' Switch 



"V 1-2 

Feed Wires 

>. ..... . . ■■■■■ 

, - , 

i- 


Fig. 286.—Three-way surface snap switches used for Carter-system two-location control. 



Fig. 287.—A three-way switch and a four-way switch arranged for a Carter system 

two-location control. 



Fig. 288. —Carter system. Two-location control using a single-pole double-throw 
knife switch and a three-way surface snap switch. 



Fig. 289. —Carter system two-location control using a single-pole double-throw knife 

switch and a four-way surface snap switch. 

single-pole double-throw knife switch combinations. Both 
are for the two-location control of a lighting circuit. Figure 
289 shows a single-pole double-throw knife switch and a four- 



















































106 LIGHTING CIRCUITS AND SWITCHES [Div. 5 

way surface snap switch installation providing a two-location 
control of a lighting circuit. 

253. The Carter System Of Two-location Control Of 
Lamps Which Are Fed From Different Branches (Fig. 290) 



will frequently effect a considerable saving in wire over the 
same system connected to the same branch. Any trouble on 
the Carter circuit of Fig. 290 may be difficult for an inexperi¬ 
enced person to locate, otherwise there should be no particular 


J-1'" Branches In Wall At End Of Hall 


-dA) 



''"Lamps In Long Hall Way---'' 

-Three-Way Switch Three-Way Switch . 


A —-- 

__ U; 


•i v. 

; Li L ? 


I - Carter System 


£ - Lamps In Long Hall Way -.. 


Branches In Wall At End Of Hall 


Ll 1_2 

Vu. , 


A 


- - ■ Three - Way Switch 


a’ Travelers 

- 


r "-'These Wires Hay Be Omitted In Carter Sys tem 

■Way 



Three - Way Switch - ■ 


:: 


H-Standard System 


Li 7 


I ig. 291.—Showing a wire-saving effected by the Carter system of connection over 
Standard system of connection. This diagram show's a two-location control of lamps 
in a long hall-way which has branch circuits in its end-walls. 


difficulty with such an arrangement. In Fig. 290, if a fuse 
“blows” some of the lamps may burn at one-half voltage. 
Which lamps will burn at the low-voltage will depend upon 
which fuse ruptures, and also on the position of the switches, 

































































Sec. 254] 


THREE - AND FOUR-WAY CIRCUITS 


197 


Si and $ 2 - If, with the switches Si and *S 2 in the positions 
shown, fuse C becomes inoperative while lamps L 3 and L 2 
are, by their individual switches, turned on, the result will be 
that the lamps in lamp-group L h and also lamps L 2 and L 3 will 
burn-at one-half normal voltage if $ 2 is operated. Note that 
fuses A and C may both be removed and lamp-group Li can 
still be lighted. The method shown in Fig. 291 is particularly 
adaptable for night-watchman’s use when it is desirable to 
enter the hallway at one end and leave from the other. 

254. Hall-way Or Stairway Lighting By The Carter System 
may be obtained as illustrated in Fig. 292. The control pro¬ 
vided by, and the operation of this arrangement, is identical 



Mounted In Gang' 

Fig. 292. —Carter connections for three-way switch-circuit for hallway or stairway 
lamps. (Every lamp adjacent to any switch-location may be either lighted or extin¬ 
guished, by operating the switches at that location.) 


with that described in Sec. 238 and Fig. 271. However, the 
quantity of wire required for the installation of Fig. 292 is only 
about 70 per cent, of that required for Fig. 271 

255. Another Three-and-four-way, Carter Connected 
Switch Circuit For Hall-way Or Stairway Lighting is shown in 
Fig. 293. The switches should be located at the turns in the 
passageway and the lamps midway between the switches. 
The operation of this installation is not as flexible as that which 
is outlined in Sec. 254. If, as explained below, all lights are to 
be left “off,” all switches must be operated successively in 
sequence. This circuit is, in general, an undesirable one foi 
the same reason given in connection with Sec. 237, and Fig. 




































198 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 5 


270—if it becomes disarranged by the operation of the switches 
in incorrect sequence, it is somewhat difficult to so turn the 
switches that the circuit will operate properly. 

Explanation. —With the switch-blades in the position as shown in 
Fig. 293 all lamps are “off.” If a person enters the passageway and 
operates switch A, lamp A' is lighted. By passing through the passage¬ 
way—which is lighted by A’ —to switch B, and operating switch B, A ' 
is extinguished and B' is lighted. Thence, proceeding to, and operating 
C, B' is extinguished and C' is lighted. Thus, by going throughout the 
entire hallway—from A to E, inclusive—and operating each switch in 
passing, all lamps will be left extinguished. 



Fig. 293. —Carter-connected hallway or stairway lighting circuit. (Each switch 
must be operated in passing. With the switches in the position shown, lamp A' will 
be lighted by operating switch A. Then, upon operating switch B, lamp B is lighted 
and A' is extinguished. Then, operating switch C, B’ is extinguished and C lighted, 
and so on.) 


All lamps may be lighted and left lighted by going through the passage¬ 
way and operating only alternate switches—that is, if going in the 
direction from A to E, by operating switches A, C, and E. All lamps may 
then be extinguished and left extinguished by: (1) Passing from A to E 
and operating B and D. (2) Passing from E to A and operating E, C , 
and A. 

If a person enters the hallway at, say, C, (when the switchblades are 
in the position shown), and operates C, lamps B' and C' will be simulta¬ 
neously lighted. Then if he proceeds in either direction and operates 
each switch in passing, one lamp— B r , if he goes toward A, and C 
if toward E —will remain lighted. If the system is thus disarranged, it 
may be again placed in order by going through the hall in the opposite 
direction from that traversed by the person so disarranging it, and operat¬ 
ing only those switches which were not operated by him. 

256. The Conductors, As They Appear At The Outlets 
Before Connecting To Switches And Lamp, For Two-location 
Control Of Carter-connected Three-way Switches is shown 
in Fig. 294. Note that three conductors project from each 

























Sec. 257] THREE- AND FOUR-WAY CIRCUITS 199 

three-way switch outlet, S, two of which, F, are the switch 
feed wires, and the third, W, is the lamp feed wire. Also note 
that two conductors, which are the lamp feed wires, W, project 
from the lamp outlet, L. The two switch feed wires at each 
outlet should be connected to the branch, B —one feed wire 
being connected to each branch wire. 



Fig. 294.—Showing conductor arrangement for Carter-connections of two-location 
lamp-control, employing two three-way switches, as it appears at the outlets before 
connection to the switches and lamps. 


257. The Various Conductors At The Switch Outlets Of A 
Two-location Control Carter Circuit May Be Identified as 

follows: First, at each switch and lamp outlet, separate all 
projecting conductors from each other as indicated in Fig. 294. 
Then short-circuit (connect together) the branch wires, B, 
at the distribution center. Now proceed to a switch outlet 
(Sj Fig. 294) and there connect various pairs of the projecting 
wires to the two magneto leads until a “ring” is obtained. 
The two wires which give the ring are the switch feed wires, F. 
The third wire is the lamp feed wire, W. Mark these wires for 
future identification and separate them from each other. 
Then repeat this same operation at the other switch outlet. 
The two conductors at the lamp outlet are, of course, the lamp 
feed wires. 

Note.—This Carter-connected Two-location Control Circuit 
May Then Be Tested Out as follows: (See Sec. 243 on “testing out” 
standard circuits). Remove the short-circuit from the branch wires at 
the distribution center and connect the magneto thereto. Now the 
magneto should not “give a ring.” If it does, there is a short-circuit on 
the branches. This should be located and removed before further test¬ 
ing. Then wrap together the bared ends of the two feed wires (F, Fig. 




















200 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 5 


294)—which have been previously identified and marked— at one switch 
outlet. If the magneto now rings, the switch feed wires at this outlet are 
properly connected. If the magneto does not ring, the switch feed wires 
at this location are probably connected to the same side of the branch 
circuit. This, of course should be corrected. Repeat the same operation 
at the other switch outlet. Then connect together the two conductors 
at L, and also the three conductors at one of the switch outlets, S. 
Disconnect the magneto from the branches, and at the other switch out¬ 
let, connect the end of W to one terminal of the magneto. Now when 
either one of the two-switch feed wires, which project from this outlet, is 
connected to the other magneto terminal, a “ring” should be obtained. 
Remove this switch feed wire and repeat with the other. If a “ring” 
is again obtained, the circuit is properly connected. The switches and 
lamps may then be installed. 

258. For Three-location Carter-connected Control, The 
Arrangement Of Conductors Before Connecting To Switches 
And Lamps is shown in Fig. 295. With the exceptions noted 



Fig. 295.—Showing conductor arrangement for Carter-connection of a three-location 
lamp control, employing two three-way switches and one four-way switch, as it appears 
at the outlets before connection to the switches and lamps. 


below, the same number of conductors project from each of 
the outlets in the three-location control as in the two-location 
control (Sec. 257). The exceptions are that in the three-loca¬ 
tion control each four-way switch outlet (S 3 , Fig. 295) has 
four conductors projecting therefrom—two switch feed wires, 
F 3 , and two switch travelers, T. 

259. The Identification Of The Various Conductors At 
The Switch Outlets Of A Three-location Carter-connected 
Control May Be Effected by substantially the same procedure 
as for that which is outlined in Sec. 257 for the two-location 





















Sec. 259] 


THREE- AND FOUR-WAY CIRCUITS 


201 


control. However, the following differences should be noted: 
After identifying the conductors at Si, Fig. 295, proceed to, 
and identify the feed wires, F 3 , at switch outlet $ 3 . The 
other two projecting conductors are the switch travelers, T. 
Connect together the bared ends of the travelers, T, which 
project from S 3 . Then, at S 2 , those two wires which will 
“ring” the magneto are the switch travelers for that outlet. 
The third wire at & 2 is the lamp feed wire, W 2 . 

Note.—This Carter-connected Three-location Control Cir¬ 
cuit May Then Be Tested Out by following the same principles as 
those which are outlined an the note subjoined to Sec. 257. 

QUESTIONS ON DIVISION 5 

1. For what applications are three- and four-way switches employed? 

2. Make a sketch showing diagram of connections of the following: 

a. A three-way switch used as a single-pole switch. 

b. A four-way switch used as a single-pole switch. 

c. Two-location control using two three-way switches. 

d. Two-location control using two four-way switches. 

e. A three-way switch circuit fed from different branches. If the three-way cir¬ 
cuit is erroneously connected to the same side of the circuit, how may the error be 
easily rectified? 

/. A three-way switch circuit which may be used when the switches are located 
near each other. 

g. A typical wiring lay-out for a small residence which has two-location control 
of up-stairs and down-stairs hall lights. Also a diagram with three location control 
of the first and second-story hall lights. Also a similar diagram for four-location 
control. 

h. Two-location control with one three-way switch and one four-way switch. 

i. Two-location control with a single-pole, double-throw knife switch used with 
a three-w r ay snap switch. When used with a four-way snap switch. 

j. A three-way switch circuit with pilot lamps located at the switches to indi¬ 
cate whether the lamps in the lighting circuit are “on” or “off.” 

k. A two-location restricted control with four, three-way switches. 

l. Four-location control for down-stairs and up-stairs hall lights using two 
three-way and two four-way switches. 

m. Three-location control with three four-way switches. 

n. Three-location control with two four-way switches and one single-pole, double- 
throw knife-switch. 

o. A restricted switch circuit for hall lights. 

p. A stairway lighting circuit whereby the stair landing on which one is standing, 
together with the one above or below, may be lighted. Explain its operation. 

q. Three-way switch circuit for garage. 

r. Remote control of a vacuum-cleaner motor. 

s. Independent control of a vacuum-cleaner motor. 

3. Explain with diagrams how the travelers, feed wires, return wires, and the proper 
branch-circuit wires of a multi-location-control circuit may, after installation, be 
identified and tested out with a magneto test set. 

4. What is the Carter system of multi-location control. 

5. What are some of its advantages and disadvantages? Make sketches to illus¬ 
trate each. 


202 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 5 


6. Make a sketch showing diagram of the Carter-system of connections of the following: 

a. Two-location control. 

b. Three-location control. 

c. Two-location control from two different branches. Explain what may happen 
if one of the branch fuses burns out. 

d. Two different hallway or stairway circuits. 

e. A combined restricted and selective circuit. 

7 . Explain, with a diagram, how to identify and “test out” the different conductors 
in a Carter-system circuit. 


DIVISION 6 


MASTER OR EMERGENCY CIRCUITS 

260. A “Master” Or So-called “Emergency” Circuit, 

(Fig. 296) is one which is controlled by a master switch (Sec. 
56). The most frequent application of master circuits is in 
residences to provide emergency lighting in case of fire or an 
attack by house-breakers. A master circuit may be utilized 
to light simultaneously: (1) All of the lamps within a building , 
Fig. 297. (2) Lamps which are located on the outside of a 

building , Fig. 298. (3) All lamps on both inside and outside. 

(4) Certain designated lamps or lamp-groups. Master circuits 
are sometimes called burglar circuits. 




Fig. 296. —Elementary master circuit. (Either switch A, B, or C, may be considered 
as a master switch, since the lamps may be lighted by either switch, and no other switch 
on the circuit will extinguish them.) 


Note.—Remote-control Master Circuits —those which employ a 
solenoid-operated switch—are discussed in Div. 8. 

Note.—The Term “Location Control” means control—the ability 
to light or extinguish the incandescent-lamp groups—by operating a 
switch or switches other than the master switch. Ordinarily, in master 
circuits, three- or four-way switches are used for location control. Usu¬ 
ally these location-control switches are installed in the same room with 
the lamp group or near it—but they may be installed at any convenient 
point. 

Note.—Sometimes, In Emergency Systems Of Lighting, It Has 
Been The Practice To Provide For The Emergency Lights Sepa¬ 
rate Circuits And Separate Fixtures In Addition To Those 
Required For The Normal Illumination (W. S. Jones, in Power 
Plant Engineering). This has resulted in a dual lighting system in 

203 











204 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 6 


the spaces where emergency lights are required and, aside from the 
expense of such an arrangement, it has the added disadvantage that the 



Fig. 297. —In an emergency all the lights in a house can be lighted simultaneously by 
a remote-controlled switch, which can be controlled by a momentary-contact switch. 
The momentary-contact switch can be located in any desired room. (Courtesy of 
Hart Mfg. Co.) 



Fig. 298.—Lamps located on outside of residence controlled by master switch in owner’s 

bedroom. 


emergency circuit is not sufficiently used to be assured of proper operation 
when the emergency occurs. Frequently, such circuits have been out of 

































































































































































































































Sec. 200] 


MASTER OR EMERGENCY CIRCUITS 


205 


order several weeks or months and the trouble was not made evident 
until there was occasion for their use. But where the same lamps are 
used for both general and emergency lighting such difficulties are not 
likely to occur. Thus as the emergency lights are used normally every 
day as general lights any trouble with any one of the lights will make 
itself apparent immediately and the trouble will, as a rule, be remedied 
at once. 

Note.—Emergency Or Master Circuits Are Frequently Speci¬ 
fied For Residence-wiring Installations. Where they have not 
been specified by the architect, the contractor can often induce the 
owner to install them if he explains their advantages. In this way, it is 
often possible for a contractor to obtain a fair profit on an installation 
that otherwise would offer but meager returns. 



Fig. 298A.—Emergency lighting in a fire-engine house. No special fixtures are 
required. The lights, L, which are used as both emergency lights and general lights, 
are each controlled by a three-way switch, S3. The master switch, E, which controls 
the emergency lights, is a standard single-pole flush switch located at the operator’s desk. 
General lights are shown at B. The switches Si are single-pole switches. 


The master switch (Sec. 56) is usually placed in the owner’s bedroom 
often near the head of the owner’s bed. He can thereby light simulta¬ 
neously at will, all of the lamps, or only certain designated lamps, in his 
residence. Whether the operation of the master switch will light all of 
the lamps or only part of them is determined by the circuit arrangement 
which is employed. This he can do regardless of the positions of other 
switches throughout the building controlling the same lamps. 

Note.—Master Circuits Are Frequently Used At Fire Depart¬ 
ment Stations (Fig. 298A). The master switch is installed in the 
operator’s room. The lamps on the master circuit are located in the 
dormitories, corridors and apparatus rooms. When a call is received 
during the night the attendant at the operator’s desk may instantly light 
the lamps throughout the station house. 




























































206 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 6 


261. Master Circuits May Be Classified According To Their 
Operating Features as follows: (1) Straight , or straight-control 
master circuits , Fig. 299 (Secs. 265 to 276) wherein the master 
switch will, when operated, only light the lamps which are on 
the master circuit. (2) Universal , or universal-control master 
circuits, Fig. 324, wherein the master switch, can be operated, 
to either light or extinguish all of the lamps which are on the 
master circuit; see Secs. 277 to 283. 



Fig. 299. —A simple emergency or master circuit. (Each lamp group has only one 
control location. Single-pole switch, M, is used for master switch. All lamps are 
connected to one branch circuit.) 

Explanation.— By Means Of A Straight-control Master Cir¬ 
cuit, a person may so operate the master switch that all of the lamps on 
the circuit will be lighted, irrespective of the position of any other switch 
or switches on the circuit. However, a straight master switch can only 
be operated to extinguish such lamps as happen to have their individual 
switches in the open position. With a universal-control master circuit — 
usually controlled by two separate switches mounted at the same loca¬ 
tion—all of the lamps may be lighted or extinguished at will, irrespective 
of the positions of the individual-lamp-circuit switches. 


262. Master Circuits May Be Further Classified According 
To The Installation Features in regard to: (1) The number of 
wires of the system which supplies the energy; that is, whether 
the energy is supplied by a two-wire or by a three-wire system. 
(2) The number of control-locations with which the individual 
lamp-groups are provided; that is whether single- or multi-loca¬ 
tion. (3) The type of master switch used; see note below. (4) 
The system of connections employed for the three- and four-way 
switches which control the individual lamp-groups; that is, 
whether Carter or standard (Sec. 249). Master-circuit wiring 



















Sec. 263] MASTER OR EMERGENCY CIRCUITS 


207 


diagrams which embody various combinations of the above 
classifications are described in the following sections. 

Note.—The Various Types Of Switches Which May Be Used 
As Master Switches: (1) Single- or multi-pole switches, of either the 
knife-blade, rotary-snap, or push-snap type. (2) Three- and, four-way 
switches. (3) Momentary-contact switch in conjunction with a solenoid- 
operated switch (see Div. 8). 

263. To Insure Positive Operation Of A Master Circuit, 
Keyless Sockets Should Be Used At All Lamp Outlets which 
are connected to the emergency circuit. Also, the sockets 
should be of a type in which the lamps can be locked. It is 
obvious that if a key socket is open, or if the lamp be unscrewed 
from the socket, it cannot be lighted by closing the master 
circuit. Thus, in every room where positive master-switch 
control is desired at all times, there should be connected to the 
master circuit at least one lamp which is equipped with a 
keyless socket into which the lamp is locked. 

264. To Comply With Code Requirements In Master- 
circuit Wiring, the master wiring must be so divided and fused 
that the maximum load which may be carried by any master 
wire and its protecting fuse will not exceed that which is 
permissible (Secs. 172 and 174) on an ordinary branch circuit. 
That is, the master wire (IF, Fig. 299) and its protecting fuse 
are considered as one side of a branch circuit, insofar as the 
maximum load which may be imposed on it is concerned. 
Thus, a single master wire must not serve more than 16 sockets 
660 watts—or in special cases 32 sockets or 1,320 watts. 

Note.—Although There Is No Specific Reference To Master 
Switches In The Code, there is no limitation as to the number of 
switches that may be placed in any installation. Hence master switches 
may be installed without violating Code requirements. However, as 
above suggested, where a master switch controls an incandescent 
lighting load greater than 660 watts, the load must be divided on the load 
side of the master switch between several master wires and each must 
be protected by fuses, so that no master wire will carry more than 660 
watts. See Sec. 172. 

266. Single-location-controlled Lamps On One Branch 
Circuit May Be Straight-mastered as shown in Fig. 299. This 
is the method which is ordinarily used in small residences or 


208 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 6 


apartments wherein there is only one branch circuit. Each 
lamp-group, Gi, G 2 , and Gz, is provided with only one control- 
location, by the three-way switches, S 1 , S 2 , and Sz . The mas¬ 
ter switch, M, is a single-pole switch. With M and the 
three-way switches open as in the diagram, all lamps are off. 
However, by closing M, all lamps will be lighted, the current- 
path being as indicated by the arrows. Also wth M closed, if 
one of the switches, as S 2 , is operated so that the switch-blade 
is moved to the dotted position, then the lamps, G 2 , will remain 
lighted by current which will flow directly from Li through the 
switch S 2 and lamps G 2 to L 2 . Thus all the lamps remain 
lighted when M is closed irrespective of the three-way switch 
blade positions. 

266. Another Arrangement Of A Straight Master Circuit 
For Single-location-controlled Lamps is shown in Fig. 300. 



Fig. 300.—Emergency circuit for single-location controlled lamps which are connected 

to one branch circuit. 

By tracing out the connections, it will be noted that one side of 
each lamp is connected to the same side, L h of the branch. 
The other side of each lamp is connected to one of the shunted 
terminals of the three-way-switch. The other two terminals 
on the switch are connected, one to the other side, L 2 , of the 
branch, and one to the master wire. The two wires which 
connect switches A and B should not be mistaken for. switch 




































Sec. 267] MASTER OR EMERGENCY CIRCUITS 


209 


travelers; they are not, because wire D connects one of the 
binding-posts of each A and B to the master wire, and wire E 
connects the other binding-post of each A and B to L 2 . A 
single-pole switch, M, is used to control the master circuit. 

267. A Straight Master Circuit For Single-location-con¬ 
trolled Lamps On Three Branch Circuits may be controlled by 
a single-pole master switch, M h as shown in full lines in Fig. 
301. The same master control is provided herein as that 



Fig. 301.—Emergency circuit for single-location-controlled lamps for three branch 

circuits. 


which was described in Sec. 265 for Fig. 299. It should be 
noted that if Mi is closed when all of the lamps have been 
extinguished by their individual three-way switches, the cur¬ 
rent for lighting all of the lamps will be carried by one fuse, F. 
This will not be objectionable if the total number of sockets 
which are served by the three branches does not exceed 16 
(see Sec. 264). 

Note. —If The Total Number Of Sockets Does Exceed 16, an 
installation according to the diagram as shown in full lines (Fig. 301) 
may (Sec. 264) be contrary to the Code. If it develops that the installa¬ 
tion is not in compliance with Code requirements, it may be corrected 
14 





















































210 


LIGHTING CIRCUITS AND SWITCHES 


[Div. G 


by the following: Remove the switch Mi (Fig. 301), and conductors, A, 
B, C, and D, and substitute therefor the three-pole fused switch, Ms, 
and the conductors which are shown in dotted lines. This provides a 
fuse, F i, F 2 , and F 3 , for each of the master wires, C 2 , and C 3 . The 
maximum current which will then flow through any fuse will not exceed 
that which flows through any one branch. See Sec. 172. 

268. Two Or More Branch Circuits May Be Interconnected 
Through A Master Circuit With No Adverse Results as shown 
in Figs. 302 and 303. As explained in the preceding section, 


.Dining Room 
Four Lights 


.''5557 

Living Room 
Four, Lights 

Librarr 
Four Ligh 

"{7757 

Kitchen 
Two Lights 

'-■{75 


Standard 

Panel 

5L 



Fig. 302 —Master switch circuit feeding from a two-wire panel board, flush switches 
being used. This arrangement must not be used where the master switch controls over 
16 sockets or 660 watts. (Bryant Electric Co.) 


interconnection violates Code requirements if the total inter¬ 
connected load exceeds 16 sockets or 660 watts. In Fig. 302 
two branch circuits, which serve a combination of one- 
and two-location-controlled lamp-groups, are interconnected 
through the master circuit. The single-pole master switch, M , 
operates to light all lamps shown in the diagram. Figure 303 
shows four branch circuits. The two branches on the left of 
the illustration are interconnected one with the other; also the 
two on the right are interconnected. Each of the two pairs of 
branches which are interconnected are served through the 
emergency circuit by one blade of the double-pole master 





























































Sec. 260] 


MASTER OR EMERGENCY CIRCUITS 


211 


switch, M. Hence not more than 16 sockets can be supplied 
by either of the master-circuit fuses, F. This is (Sec. 264) in 
compliance with Code requirements. 



Fig. 303.—Master switch circuit feeding from a two-wire panel board, flush switches 
being used. This arrangement may be used where the master switch controls a maxi¬ 
mum of 32 sockets or 1,320 watts. (Bryant Electric Co.) 

269. A Stairway Straight Master Circuit is shown in Fig. 

304. Individual single-location-control of the lamps on each 
floor is provided by the three-way switches, Si, S 2) and S 3 . 
The single-pole master switch, M, is located in the basement 
so that it may be conveniently operated by the janitor. Thus, 
all of the stairway lamps may, by closing M, be kept lighted. 
Or, if M is opened, the lamps on any floor may be lighted or 
extinguished by the switch which is on that floor. 

270. A Method Of Installing A Straight Master Circuit In A 
Building Which Has Already Been Wired is outlined in Fig. 

305. As shown, only one control-location is provided for 
each lamp-group. Three-way switches are substituted for the 
originally-installed single-pole switches. The dotted lines 
represent the additional wiring which is necessary to provide 
the master circuit. A double-pole switch, M, is used as a 
master switch. If M is closed, all of the lamps will be lighted. 






































































































212 


LIGHTING CIRCUITS AN1) SWITCHES 


[Div. 6 


If M is open, the lighting and extinguishing of any lamp- 
group may be controlled by its three-way switch. As drawn 
(Fig. 305), the master-switch connections render each branch 
circuit separate from and independent of the other. However, 
as will be noted by tracing out the connections, if conductors 
A and B are interchanged on the master-switch binding-posts, 
some of the lamps on both branch circuits may, if a fuse rup- 





/ 


Fig. 304.—A stairway master circuit. (Master switch M is located in the basement; 
when M is closed the lamps on all floors are lighted and cannot be extinguished by operat¬ 
ing the three-way switches.) 

tures, burn at one-half normal voltage when M is closed. If 
so desired two single-pole switches—one for each branch 
circuit—could be used to control the master circuits. 

271. The Usual Method Of Providing A Straight Master 
Circuit For Two-location-controlled Lamp-groups is shown 
in Figs. 306 and 307. The two-location control for the 
lamp-group, G, (Fig. 306) is obtained by one three-way switch, 
T, and one four-way switch F. The master switch is a single¬ 
pole switch, M. As suggested in Fig. 308, this method of 
connection may be extended to include any number of lamp- 
groups which may be connected to one branch circuit. If it is 













































Sec. 271] MASTER OR EMERGENCY CIRCUITS 


213 



Fig. 305.—Showing method of installing an emergency circuit in a building which 
has already been wired. (Three-way switches, S, are installed in the original single¬ 
pole switch outlets. Dotted lines indicate the necessary additional wiring.) 



Fig. 306. —Simple master circuit for one lamp-group which is provided with two 

location control. 



























































































































































































214 


LIGHTING CIRCUITS AND SWITCHES 


|D iv. 6 


desired to master more than one branch circuit, as many single¬ 
pole master switches may be used as there are branches to be 
mastered. Or, a double-pole switch wired as two single-pole 
switches (Fig. 309); a three-pole switch wired as three single- 



Fig. 307.—Straight-control master circuit for two-location controlled lamps. (Two- 
location control of the lamp-group is obtained by a three- and a four-way switch.) 


pole switches; a four-pole switch wired as four single-pole 
switches, and so on, can be used. 

Explanation. —The connections for the above method of mastering 
may be outlined as follows: Connect one side of each lamp-group (G, 
Fig. 308) to one side of the branch, Li. Connect the other side of G 



Fig. 308.—Straight-master circuit for several two-location-controlled lamp-groups on 
the same branch circuit, using a single-pole master switch. 


to one of the shunted terminals (usually marked “L” on the switch) 
of the three-way switch, T. The switch travelers, W, have one pair 
of their ends connected to the other two binding-posts of T. The 
other two ends of W are connected to diagonally-opposite binding- 
posts of the four-way switch, F. A wire, D, is connected; one end to 



































Sec. 272 J 


MASTER OR EMERGENCY CIRCUITS 


215 


either of the other two binding-posts of F, and the other end to the 
branch, L 2 . Another wire, E, is connected between the remaining- 
unwired binding post of F to the master wire, H. The single-pole master 
switch, M, is connected, one terminal to H and the other terminal to L 2 . 



Fig. 309.—Wiring diagram of emergency circuit for small residence wherein all lamps 

are on the emergency circuit. 


272. A Straight Master Circuit For One- And Two-location- 
controlled Lamps Which Are Connected To The Same Branch 
Circuit is illustrated in Fig. 309. Such an installation typifies 
that of the medium-size residence, wherein two branch circuits 
are employed. The double-pole master switch, M, is wired 
as two single-pole switches. Interconnection between the two 
branches through the medium of the master circuit is thereby 
prevented. Actually, this installation contains two separate 
and distinct master circuits—one for each branch. The 
principle of connections used in Fig. 309 is a- combination of 
that described in Sec. 265, Fig. 299, with that, of Sec. 271, 
Fig. 308. 















































































































216 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 6 


273. Various Methods Of Providing A Straight Master 
Circuit For A Single Group Of Multi-location-controlled 
Lamps, Using A Single-pole Master Switch are shown in Figs. 


Three -Way Switches-. 



Fig. 310.—Straight master circuit for two-location-controlled lamp-group, wherein the 
two control-locations are provided by two three-way switches. 

310, 311, 312, and 313. Such arrangements are, generally, 
applicable only for hallway or stairway circuits where master 



Fig. 311.—Straight mastering of three-location-controlled lamp-group. (Control- 
locations provided by two three-way and one four-way switch.) 

control for only one lamp-group is desired. In Fig. 310, the 
master switch, M, a single-pole switch which is connected 



Fig. 312.—Single-pole master switch connected in parallel with one four-way and two 

three-way switches. 

across the travelers, when closed, short-circuits the switch 
travelers and holds them closed against either of the three-way 
switches. As shown in Fig. 311, a three-or-more-location- 

































Sec. 273] 


MASTER OR EMERGENCY CIRCUITS 


217 


controlled lamp group may be mastered by connecting the 
master switch across the switch travelers between any two of 
the control locations. In Fig. 312, the three-location-control 
of the lamp-group is effected by two three-way switches and 



Fig. 313. —Emergency circuit for a three-location-controlled lamp group wherein each 
control-location is provided by a "four-way switch. 

one four-way switch. In Fig. 313, three four-way switches 
are utilized to provide the three-location control for the lamps. 
Compare Fig. 313 with Fig. 257 and note that the master 
wires in Fig. 313 are connected to the idle binding-posts of the 
end-switches of Fig. 257. 



Three - Way Switch - 


Fig. 314. —Straight mastering of combination one- and two-location-controlled 
lamps with a double-pole master switch. (One blade of M is used to short-circuit the 
switch travelers.) 

Note.—Straight Master Control Of A Two-location-con¬ 
trolled Lamp-group, L, By Short-circuiting The Switch Travelers 
may be obtained as diagrammed in Fig. 314. When the master switch, 
M, is closed the switch travelers between F and T are short-circuited 











































218 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 6 


through one blade of M and the wires, K and L. The single-location- 
controlled lamp groups, Q, N and 0, individually controlled either by 
three-way switches, A and C, or by a four-way switch, B. As shown, 
the double-pole master switch is wired as two single-pole switches. 
When M is open all of the lamp groups shown are controllable by their 
respective “location” switches. When M is closed all of the lamp groups 
shown are lighted, irrespective of the positions of the location switches. 

274. A Straight Master Circuit For Two Or More Lamp- 
groups Wherein One Or More Of The Lamp-groups Is, By 
Two Three-way Switches, Provided With Two-location 
Control (Figs. 315, 316, and 317) must be equipped with one 



Fig. 315.—Double-pole master switch wired as two single-pole switches for the 
emergency lighting in a combined one- and two-location controlled installation. 


single-pole master switch for all of the single-location- con¬ 
trolled lamp-groups, and with one additional single-pole 
master switch for each lamp-group which has three-way 
switch two-location control. In Fig. 316, the master switch, 
Mi, controls the emergency circuit for the single location- 
controlled lamps, L. controls the emergency circuit for the 
three-way-switch two-location-controlled lamp-group, G. In 
Figs. 315 and 317, the same result is effected by wiring the 
double-pole switch M as two single-pole switches. 










































Sec. 274] 


MASTER OR EMERGENCY CIRCUITS 


219 


Explanation— Figure 318 illustrates why the above specified switch¬ 
ing must be employed. In Fig. 318 one single-pole master switch, M, is 
used. When M is closed all the lamps will be lighted. But when M is 



Fig. 316.—Two single-pole master switches used to control an emergency circuit for 
combined one- and two-location-controlled lamps. 


open, lamps A, B , and C cannot be extinguished by their repective 
switches, unless switches E and F are operated to extinguish group D. 
With the switch bars in the various positions as shown in Fig. 318, group 



Three-Way; Switches 

.■■Master Switch /'», 

''A 



tjip) tji|) 


J 

. -r , Larnps >.,. 




'"-Lamps'- <^G 


^ D A, E 

Branch Circuit ^^ Three-Way Switches . ^^=5^ 


Fig. 317.—Double-pole knife switch as master switch for emergency lights, in a com¬ 
bined one- and two-location-controlled installation. 


C should be extinguished but actually is not. Since current can follow 
the path indicated by the arrows, C will be lighted. If switch H is 
operated to the position corresponding to that of (7, lamps C will still 



























































220 


LIGHTING CIRCUITS AND SWITCHES 


[Diy. 6 


be lighted. Thus, lamp-groups A , B and C may be controlled by their 
respective switches only when either E or F is operated to extinguish D. 

275. Master Circuits For Two Branches Which Serve A 
Combination Of One- And Two-location-controlled Lamps 

are shown in Fig. 319. Since all of the lamps on the branch, 
XY, which serves the left-hand side of the house are provided 
with only single-location control, a single-pole switch, Mi, 
may (Sec. 265) be used as a master switch. The right-hand 
branch, VW, has connected to it a lamp-group which is 
provided with two-location control by the two three-way 



Fig. 318.—Incorrect master circuit. (Lamps A, B, and C, cannot be extinguished except 

when lamps D are extinguished.) 


switches, A and B. Therefore the master switch which con¬ 
trols the emergency circuit for this VW branch must (Sec. 274) 
be provided with two switch poles. These two switch poles are 
obtained by wiring the double-pole switch, M%, as two single¬ 
pole switches. Thus, by using two master switches, Mi and 
M 2 no interconnection between the two branches will result; 
really three master switches have been used because, M 2 is, 
in effect, two single-pole switches. 

Note.—Where A Combination Of One- And Two-location- 
controlled Lamp-groups Are Connected To The Same Branch 
Circuit (Figs. 309, 315, 316, 317, 319, and 320), it will usually be more 
economical to use, for the two-location-controlled lamp-groups, one three- 
way switch and one four-way switch, connected as shown in Figs. 308 and 
309, than to use two three-way switches connected as shown in Figs. 315, 
316, 317, and 319. The arrangements of Figs. 308, 309, and 320, require 
only one single-pole master switch for each branch which is provided with 






























Sec. 276] 


MASTER OR EMERGENCY CIRCUITS 


221 


an emergency circuit. Since the average-size residence does not usually 
have more than three branches, one three-pole master switch can gener¬ 
ally be used to control the entire emergency-circuit system. Whereas, if 
the wiring is made in accordance with Figs. 315, 316, 317, or 319, several 
master switches and a large additional quantity of wire may be required. 



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276. If It Is Desired That Only A Part Of The Lamps In An 
Installation Be Connected To The Master Circuit, the wiring 
may be arranged similarly to that of Fig. 319. The lamps, 
S, (Fig. 319) which are controlled by key sockets or single- 


































































































































222 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 6 


pole switches (not shown in the illustration) are not connected 
to the master circuit, and consequently will not, necessarily, 
be lighted when the master switches are closed. Such pro¬ 
vision of lamps, which are not on the master circuit, may result 



Fig. 320. —Single-pole master switch controlling the emergency circuit for a combina¬ 
tion of one- and two-location-controlled lamps. (Lamp L is lighted only when master 
switch is closed.) 

in a reduction of the wire- and switch-cost. Yet, since there 
are, in every room, lamps which are on the master circuit, the 
installation is equally as effective for burglar protection as 
though all of the lamps in it were on the master circuit. 



Fig. 321. —Simple universal master circuit. (Both Mi and Mi open, all lamps off. 
Both closed, all lamps on. Either Mi or Mi open and the other closed, lamps controlled 
by A and B.) 

277. The Principle Involved In The Connections Which Are 
Ordinarily Used To Obtain Universal Control Of A Master 
Circuit (Sec. 261) may be understood by a consideration of 
Fig. 321. Two master switches are necessary. If both 











































Sec. 2771 


MASTER OR EMERGENCY CIRCUITS 


223 



Fig. 322.—Universal mastering of single-location-controlled lamp-groups using two 

single-pole master switches. 



Fig. 323.—Elementary wiring diagram of a universal-control master circuit. 































































224 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 6 


of the master switches, Mi and ilf 2 , are open, only one side oi 
the lamps can be connected to the line, L\. Consequently, the 
lamps will not burn while both Mi and M 2 are open. If both 
Mi and M 2 are closed, the lamps will be connected to both 
Li and L 2 through switches A and B, irrespective of the posi¬ 
tions of A and B. Therefore, the lamps will, while both Mi 
and M 2 are closed, always be lighted. If either Mi or M 2 
is closed and the other open, the lamps may then be lighted or 
extinguished by either A or B. In Fig. 322, the operation is 
the same, except that each of the lamp-groups is provided with 
only one control location. 

Note.—Another Elementary Universal-control Master-switch 
Circuit is shown in Fig. 323. For a universal-control circuit two single¬ 
pole master switches Mi and Af 2 , are used in each branch circuit. That 
is, each pair of single-pole master switches can control a group of sockets 
not exceeding sixteen in number and requiring not more than 660 watts. 
If the master circuit controls more than sixteen sockets, or 660 watts, 
it will be necessary to install a set of branch cutouts and one additional 
pair of single-pole master switches for each sixteen sockets or 660 watts, 
or portion thereof, so that the Code requirements may be satisfied. 

Note.—A Residence Can Seldom Be Wired In Exact Accordance 
With The Elementary Circuit shown in Fig. 323, because this wiring 
diagram is drawn for only one branch circuit. In cases where the lamps 
are supplied with energy from more than one branch circuit and must be 
subject to master-switch control, the wiring becomes more complicated. 
The connections can be very readily made for any number of branch 
circuits, provided the wireman remembers and follows the few simple 
rules which are given in Sec. 279. 

278. A Diagram Of A Universal-control Master Circuit 
For Combined One- And Two-location-controlled Lamps is 

shown in Fig. 324, also in Fig. 325. The principles 
involved in these diagrams will usally be found applicable to 
medium-sized residences which are wired with two branch 
circuits. In Fig. 324, the single-pole master switches, C and 
D } provide universal control for one of the branch circuits. 
E and F provide universal control for the other branch. The 
operation of master switches C and D, and of E and F, pro¬ 
duces the same results on their respective branches as that 
which was explained in Sec. 277. In Fig. 325, except for the 
master switches, the wiring is the same as that in Fig. 324. 
In Fig. 325, the two double-pole master switches, Mi and M 2 , 


Sec. 278] MASTER OR EMERGENCY CIRCUITS 


225 



Fig. 324.—Four single-pole master switches control the universal emergency circuit 

for two branch circuits. 



Fig. 325.—Two double-pole master switches control the universal emergency circuit 

for two branch circuits. 


15 




























































































































226 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 6 


are wired as four single-pole switches, so that: (1) When both 
switches are closed, all lamps are lighted. (2) When both 
switches are open, all lamps are extinguished. (3) When one 
switch is open and the other closed, the lighting of the lamps is 
controlled by their respective individual-controlling switches. 



279. The Method Of Wiring For Universal-control Master 
Circuits Where Porcelain-base Edison Plug Cutouts Or 
Branch Blocks Are Used is illustrated in Fig. 326. Two 
branch circuits are shown. One is fed through the cutout A, 































































Sec. 280 ] MASTER OR EMERGENCY CIRCUITS 


227 


and the other through C. The cutout B is placed to carry 
the fuses for the master wires, shown in dotted lines in the 
diagram, for the two circuits. In laying out and wiring these 
circuits it will be convenient to designate one leg of the main 
circuit the positive or (+) leg, and the other the negative or 
(—) leg, as shown at D in Fig. 326. These legs need not actu¬ 
ally be the positive and negative legs of the circuit, but these 
polarities are assigned to them arbitrarily merely to distinguish 
one side of the circuit from the other as an aid in tracing out 
connections. 

Explanation. —It will be noted from a study of Fig. 326 that each 
individual-control switch, whether it be a three-way or a four-way 
switch, has one of its terminals connected to a master wire, and another 
terminal connected with a side of the branch of the same polarity as the 
master wire for the same switch. The suggestion just noted is the most 
important one, and if the wireman follows it closely he will have little 
difficulty in connecting his circuits. One side of each group of lamps is 
always connected to the single terminal of a three-way switch, as shown 
at E and F in Fig. 326, while the other side of each group of lamps is 
connected always to a side of the branch of the opposite polarity to that 
of the master wire, as shown at G and H. 

Note.—The Wiring Scheme Suggested In Fig. 326 Can Be 
Extended To Serve As Many Circuits As Desired, provided that 
each branch circuit does not contain more than sixteen sockets, nor be 
loaded with more than 660 watts. There should be a pair of single-pole 
master switches for each branch circuit. 

280. In Universal Master Circuits Multi-pole Knife 
Switches Can Be Used Instead Of A Number Of Single-pole 
Snap Switches. Each blade of such a knife-switch would take 
the place of a single-pole flush or snap switch. For example, 
if there were three branch circuits in an installation, two triple¬ 
pole, single-throw knife switches would be installed. Each 
of the blades of one of these triple-pole switches would take the 
place of an M x switch (Fig. 323) while each of the blades of the 
other triple-pole switch would serve in place of an M 2 switch. 
Where multi-pole knife switches are used as suggested, the 
owner can light or extinguish all of the emergency-circuit 
lamps in his building by throwing the handle of one of these 
multi-pole switches. 

281. A Building Which Is Already Wired For Electric 
Lamps May Be Provided With A Universal Master Circuit As 


228 


LIGHTING CIRCUITS AND SWITCHES 


[Div. C> 


Suggested in Fig. 327. This diagram shows the circuits for 
such an installation where panel boxes have been installed. All 
of the master wires can be fed from one side of the circuit, the 
negative side, for example, as shown in Fig. 327. Single¬ 
pole cut-outs are used to protect the master wires from exces- 


■O" 

K> 


O 






Edison Plug 


e-J--’-' -Mains 


5— 






b 



<Cr 

/hX. 


"Jl- 



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5 





it- 



1 

Three-Way 
Switch \ 


1 


^Four-Way 

Switch 


O- 

^4 


-O-' 

Lamps. „ Nfr 

Y ■NN 

\Three-Way 

Switch ^ 


k- 


5Ingle-Pole 
Plug Cutouts \ 



-u- 

Single-Pole 
' Switches' 




■ o 
•o • 

" O ■ 

-o- 

'~Q- 


'Qr 


Fic. 327. Universal-control master-switch wiring for an existing panel-box installation. 


sive currents, these plug cut-outs are most conveniently 
placed at some point adjacent to the panel-box location as out¬ 
lined in Fig. 327. The dotted lines in Fig. 327 indicate the 
wires that must be added to an existing installation to provide 
the universal control. At each location where a single-pole 
switch was formerly used in the existing installation, a three- 











































































Sec. 282] MASTER OR EMERGENCY CIRCUITS 


220 


way switch must be installed, as shown. At certain points 
where three-way switches were formerly installed, four-way 
switches must be used. At certain other points where there 
were formerly four-way switches, the four-way switches are 
permitted to remain. Reference to Fig. 327 will make the 
meaning of this statement clear. 

282. Where Branch Circuits Are Fed From A Panel Box the 
wireman may experience trouble in making the correct con¬ 
nections unless the suggestions given in Sec. 279 in regard to 
polarities are closely followed. It is frequently necessary to 
cross the conductors, as shown at A and B in Fig. 327, 
to make these polarities correct. This crossing is necessary 
because of the method in which connections are often made to 
the branch circuits on the panelboard. Inasmuch as master 
switches are usually installed in the owner’s bedroom, it is 
best to install the panelboard in this room, or near it, so that 
the master switches will be near the distributing cabinet or 
panel box. 

283. Universal Mastering Of A Lamp-group Which Is 
Provided With Multi-location Control May Be Effected By 
Using The Carter System Of Three- And Four-way Switch 



Fig. 328.—Universal master control of one multi-location-controlled lamp group where¬ 
in the three- and four-way switches are Carter-connected. 

Connections (Sec. 249) as shown in Fig. 328. If the double¬ 
throw, double-pole master switch, M, is closed to position A, 
the lamps will be lighted regardless of the positions of the 
three- and four-way switches. If M is open, all lamps will be 
off. If M is closed to position B, the lighting of the lamps may 
be controlled by the three- and four-way switches. In Fig. 

























230 


LIGHTING CIRCUITS AND SWITCHES 


|Div. 6 


329, the same principle is extended to include two multi¬ 
location-controlled lamp-groups, and two double-pole, double¬ 
throw master switches are required. This method is, because 
of the type and number of master switches required, usually 
uneconomical. 



Fig. 329. —Universal master control of two multi-location-controlled lamp groups 
wherein the three- and four-way switches are connected according to the Carter 
system. 


284. A Combined Carter And Standard System Which 
Provides A Combined Universal And Straight Master Circuit 

is shown in Fig. 330. If the master switch, M, is closed to 
position A, all lamps will be lighted. If M is closed to the 
right, lamps C are controlled by switches, D, E, and F; lamps 
K by switches N and L; and lamp G is controlled by H. If M 
is open, lamps C are extinguished and can not be lighted by 
operating switches D, E, and F; and also lamps K and G are 
controlled by their respective switches. 

285. Control Of A Straight Master Circuit From Two Loca¬ 
tions (Fig. 331) may be obtained by the use of two three-way 
switches, connected as shown, instead of the usual single-pole 
switch. In fact, such an arrangement may be provided in any 
master circuit, by using one pair of three-way switches for 
each switch-pole which is required for single-location control 
of that master circuit. Except for the use of the two three- 






































Sec. 285] 


MASTER OR EMERGENCY CIRCUITS 


231 


way switches (.A and B, Fig. 331) instead of the single-pole 
switch (M, Fig. 313), the wiring of Fig. 331 is identical with 
that of Fig. 313. 



Fig. 330.—Combined Carter and Standard system of three- and four-way-switch 
connections to provide a combined straight and universal control of the emergency 
circuit. 

Note.—Two-location Control Of A Universal Master Circuit 
may, as suggested above, be obtained by using one pair of three-way 
switches for each single-pole switch, or one pair of three-way switches 
for each pole of an n-pole switch which is wired as n single-pole switches. 
For example, in Fig. 332, two pairs of three-way switches, T i and T 2 , have 



Fig. 331.—Two location control of a straight master circuit. 


been substituted for the single-pole master switches, Mi and M 2 , of 
Fig. 321. Each TVswitch (Fig. 332) should be mounted in gang with 
a TVswitch. Thereby, at either location, a person may open or close one 
or both of the 7V and TYcircuits. The same master control as was 
explained in Sec. 277, for Fig. 321 is thereby provided. A third master- 




















































232 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 6 


control location may be obtained by connecting into the circuit two 
four-way switches; one between the 7Yswitches and one between the 
T 2 -switches. 

Explanation. —The two master-control locations {A and B, -Fig. 331 
and T 1 T 2 -T 1 T 2 Fig. 332) may be located in different rooms, or one may 
be located in the owner’s bed-room and the other near the front door. 
If one of the control locations of the universal master circuit (Fig. 332) is 
located in the owner’s bed-room, it may be found convenient to install 
the other near the front door of the house. Then when all of the occu¬ 
pants leave the house at night, all of the lamps may be extinguished from 
the front-door location. Or, if only a few lamps are connected to the 
emergency circuit, these lamps may, to provide burglar protection during 
their absence, be lighted upon leaving. 



286. A Master Circuit May Be Provided For A 110-220 Volt, 
Grounded-neutral, Three-wire System (Fig. 333) by con¬ 
sidering each side circuit (Sec. 12) as a separate two-wire 
circuit. The master circuit for each side circuit may then be 
connected according to any of the methods previously outlined 
for a two-wire system. Various master circuits for three-wire 
systems are described in the following sections. 

287. The Master Switch For A Side Circuit Of A Three- 

wire System may be connected, either: (1) To the outside 
wire—hot side —Figs. 334-7 and 335. (2) Or to the neutral 

wire—dead side —Fig. 334-77. One method is probably as 
good as the other. However, in any installation, a certain 
one of the methods should, usually, be followed throughout. 
This will lessen the possibility of making wrong connections. 

288. Various Wiring Diagrams Of Master Circuits For 
Three-wire Systems are shown in Figs. 333, 336, 337, 338 and 
339. The principle involved in all is essentially the same. In 




























Sec. 288] 


MASTER OR EMERGENCY CIRCUITS 


233 



Fig. 333.—Wiring diagram of an emergency circuit for a three-wire installation. 


.-■Switch Feed Wire 



Cutout 


.■■Neutral 
* 


Lamps - i '' 
Master Wires --', 






1-2 



• 

-J- 

ucii 

J 

-Q- 



mSr 


.■Lamp Feed Wire 

» r 



... 5/ng7c-/b/(? \u-' '•'7/ Three-Wau Switch’ 

--Master Switches y 

I - Master Switch In “HofSide H-Master Switch In Grounded Side 

Fig. 334. —Two methods of connecting the master circuit of a three-wire system 




Line -+ 


Fig. 335. —Master circuit for a three-wire two-branch installation. (Double-pole 

master switch in “hot” side.) 



































































































234 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 6 


Fig. 333, those lamps, A, B, and C, which are connected to one 
side circuit are not, through the master-circuit wiring, con¬ 
nected to those lamps, D, E, F, G, and H, which are connected 



Fig. 336.—Double-pole master switch controlling the emergency circuit of a three-wire, 
four-branch installation. (Master wires are indicated by dotted lines.) 



Fig. 337.—Emergency circuit for three-wire, four-branch installation. (Master 
wires indicated by dotted lines. Since the single-location-controlled lamp groups are 
each provided with a separate master wire and switch blade, single-pole switches may 
be used for their control.) 


to the other side circuit. In Fig. 336, although the branch 
circuits which are fed from the same side circuit are inter¬ 
connected through the master-circuit wiring when the master 












































































































































Sec. 288] MASTER OR EMERGENCY CIRCUITS 


235 


Feed- -- 


Branches- «;•> 

* 

Fuses To Protect 
Master Circuit' '• 

Library & Lights 

v 

( ^ (^> (^> <^)' 

Kitchen 
:4 Lights 

V 


. - -Standard Pane/ 


-Branch-Circuit 
-' Sir itches 


'-"Branches 

Sewing Room 
4 Lights \ 

X 

HS 



Fig. 338.—Master switch circuit feeding from three-wire panel board, flush switches 
being used. This arrangement may be used where the master-switch controls as many 
as 32 sockets. (Bryant Electric Co.) 


Distribution Center-- 



'Lamp Controlled From 
Two Locations, E And F 


Lower-Hall Lamps Controlled : 

From Two Locations A. And B 


Fig. 339.—Straight master circuit for a three-wire, two-branch installation which 
contains single- and multi-location-controlled lamp groups. 
















































































































































236 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 6 


switch is open, the two side circuits are not so interconnected. 
In Fig. 337, each branch is provided with a separate master 
wire and switch blade. And since each branch serves only 
one lamp-group, single-pole switches may (Sec. 291) be used 
for the control of each lamp-group which is provided with 
single-location control. Figure 338 shows an arrangement 
which is suitable for a four-branch installation wherein the 
number of sockets served does not exceed 32, and the total 
wattage does not exceed 1,320. 

289. Wiring Diagrams Of Master Circuits Which Will Not 
Provide Satisfactory Operation For Three-wire Systems 
are shown in Figs. 340 and 341. The reason that the operation 


Side Circuit r . , 

..-Three-Way Switch...,. Lamps ('£Sl . Side Circuit Three-Way Switch 



Branch 

\ 

t 


=* 



'"-Single-Pole Master Switch 


Fig. 340.—Wiring diagram of an incorrect emergency circuit for a three-wire system. 
(As shown, only one lamp group can be extinguished at a time.) 


is unsatisfactory is because the two side circuits are inter¬ 
connected through the master-circuit wiring when the master 
switch is open. In Figs. 340 and 341, the emergency circuit 
wiring is so arranged that the branch circuits, E and F, which 
are, respectively, fed from the two side circuits, C and D, of 
the three-wire system, are, when the master switch, M , is 
open, interconnected through the master wire, W . This, as 
explained below, makes it impossible to extinguish all of the 
lamps. 

Explanation. —In Fig. 340, if the switch blades of switches A and B 
are in the position shown by the dotted lines, lamp-groups A’ and B' will 
be lighted from their respective side circuits, C and D. If either switch, 
A or B , is then operated so that the blade is in the position shown by the 
full lines, the corresponding lamp-group, A' or B', will be extinguished. 
If, however, with, say switch A in the position indicated by the full lines 
and lamp-group A' extinguished, switch B is operated with the intention 
of extinguishing B', lamp-group A' and B' will be connected in series- 
parallel across the outside wires. In the diagram, the outside wires are 

























Sec. 290] MASTER OR EMERGENCY CIRCUITS 


237 


marked + and —. Since the outside wires are at a potential difference 
of 220 volts, the lamps, A' and B' will, if all of them are 110-volt lamps 
and of the same wattage rating, instead of being extinguished, burn at 
normal voltage. The current-path is indicated by the arrows. There¬ 
fore, only one of the lamp-groups {A' or B\ Fig. 340) can be extinguished 
at any one time. However, if the master switch is closed, all of the lamps 
will be lighted. 



Fig. 341.—Incorrect method of mastering a three-wire, two-branch installation. 


290. The Emergency Circuit For A Three-wire System 
Should Be So Arranged That The Two Side Circuits Will Not 
Be Interconnected When The Master Switch Is Open. Such 
errors, which were outlined in Sec. 289 for Figs. 340 and 341, 
may be corrected by: (1) Connecting the branches , which are 
in error interconnected , to the same side circuit , as suggested in 




































































238 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 6 


Distribution Center- .> 


Upper Hall Lamps Controlled From 
Two Locations,C And D— v 


Three-Wau 

Switch 



Lower- 

Hall 

Lamps 

Controlled 

From Two 

Locations, 

A And B 


''-Three-Way Switch 


Fig. 342.—Single-pole master switch provides satisfactory control of an emergency 
circuit for a three-wire two-branch installation when both branches are connected to 
the same side circuit. 



Fig. 343.—Diagram of an incorrect emergency circuit for a three-wire, three-branch 
installation. (Error may be corrected by removing master wires, E and F and wiring 
as shown by dotted lines.) 































































































Sec. 2911 MASTER OR EMERGENCY CIRCUITS 239 

Fig. 342. (2) By providing a separate master wire and switch 

blade for each branch circuit, as indicated by the dotted lines 
in Figs. 343 and 344. The method which is suggested in Figs. 
343 and 344 will generally be found preferable to that in Fig. 
342. This is because that if the remedy is made according to 



Fig. 344—Correct method of mastering two branch circuits which are fed from a three 
wire grounded-neutral system. (Bryant Electric Co.) 


Fig. 342, the load is likely to be unbalanced on the side circuits 
and also the load carried by the master-wire fuse (F, Fig. 342) 
may exceed (Sec. 264) the allowable 660-watt maximum. 

291. Except As Mentioned Below, Single-pole Switches 
Cannot Be Used In Connection With A Master Circuit To Con¬ 
trol Individual Lamp-groups. In Fig. 345-7 the single-pole 




















































































240 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 6 


switches, Si and S 2 , are connected to control the two lamp- 
groups, A and B. Although the master switch, $ 3 , will, when 
closed, operate to light all of the lamps, an installation accord¬ 
ing to this scheme of connections will not operate satisfactorily 
for the following reason: The master switch, S 3 , being open, 
and Si and S 2 closed, both A and B will be lighted. It is now 
desired to extinguish B, consequently S 2 is opened. However, 
opening S 2 does not extinguish B, because the current will 
flow through the circuit as indicated by the arrows. Therefore 
to extinguish both A and B, switches, Si, S 2 , and S 3 , must all 
be open. A diagram of a satisfactorily-operating installation, 
wherein three-way switches are used, is shown at II. 



Fig. 345. Showing single-pole and three-way switches used in a master-switch circuit. 
(Single-pole switches as shown herein do not provide satisfactory operation.) 


Note.—Single-pole Switches For Location-control Of Lamps 
Which Are In A Master Circuit Will Provide Satisfactory 
Operation Only Under Certain Conditions. Thus, the operation 
will be satisfactory only when there is but a single lamp-group connected 
to a branch, and when the lamp-group on such a branch is served by a 
master wire which is not, when the master-switch blade is open, connected 
to any other branch. A schematic diagram of such an arrangement is 
shown in Fig. 181 and in Fig. 296. A diagram of an actual installation 
of single-pole-switch lamp-control in connection with a master circuit, 
which will provide successful operation, is outlined at A, B, and C, Fig. 
337. Note that in Fig. 337, A, B, and C, are each provided with a 





































Sec. 292] MASTER OR EMERGENCY CIRCUITS 


241 


separate master wire and switch-blade; also that only one lamp-group is 
connected to a branch (see also Sec. 346). 

Note. Only One Lamp Of A Lamp-group May, By Employing A 
Special Switch, Be Connected To A Circuit as shown in Fig. 346. 
As shown in I , the master switch, M , is open, the special switch, S , 
is closed, and all lamps are lighted. In II, the special switch, S, is 
open, and, if M was open, all lamps would be extinguished. But since 
M is closed, the emergency lamp, L, is lighted and lamps, 1, 2 and 3 are 
extinguished. 4 he use of such a switch may be desirable where the 
master circuit is often closed throughout long periods of time. Thus, by 
burning only one lamp on the fixture a much smaller energy-consumption 
will result than if the entire group was connected to the master circuit 



I- Position!: All Lamps On: Master Switch Open: Special Switch Closed. 



H-Position2: Emergency Lamp On: Master Switch Closed. 
Special Switch Open. 


Fig. 346.—Operation of special switch for use in conjunction with master circuits. 


by the ordinary method of the three-way switch. Also, if all of the lamps 
in the group are mounted on one fixture, all of the lamps may be lighted 
by one switch. This result is ordinarily obtained by the use of two 
switches ( E , Fig. 319). If one lamp on the fixture is connected directly 
to the master circuit as at L, Fig. 320, it will, except when the master 
switch is closed, be unlighted, thus presenting an unsightly appearance 
(see also Sec. 305). 

292. The Procedure To Be Followed In Identifying Con¬ 
ductors And In Testing Out Master Circuits cannot, because 
of the several wiring-schemes which may be employed, be 
definitely specified. A complete wiring diagram for any 
master-circuit wiring job should be made before the actual 

installation is begun. Then if the wiring diagram is followed, 

16 































242 


LIGHTING CIRCUITS’AND SWITCHES 


[Div. 6 


and each wire is correctly marked when it is installed, no 
trouble will result. However, if this is not done, the con¬ 
ductors may be identified and the circuit tested out by a 
judicious application of the principles which were outlined in 
Div. 5 for three- and four-way-switch circuits. 

QUESTIONS ON DIVISION 6 

1. Define a master switch. Define a master circuit. 

2. Wherein are master or emergency circuits frequently employed? 

3. How may master circuits be classified as regards operating features? 

4. How may they be classified according to installation features? 

5. What is a straight, or straight-control master circuit? 

6. What is a universal, or universal-control master circuit? 

7. Name the different types of switches which may be used as master switches. 

8. What advantage have keyless sockets over key sockets for use on a master circuit? 

9. Give the Code requirements which must be met in a master-circuit installation. 

10. Draw a wiring diagram of, and explain the operation of each of the following for a 
two-wire system: 

a. Straight master circuit for single-location-controlled lamps on one branch circuit. 

h. Same as a, except lamps connected to three branch circuits. 

c. If the load on a master-wire fuse exceeds 660 watts, how may it be corrected? 

d. Two branch circuits which have connected to them single and two-location- 
controlled lamps, wherein the branch circuits are interconnected through the emergency 
wiring when the master switch is open. 

e. A stairway master circuit. 

/. Change an ordinary lighting installation to one which' is provided with a straight 
emergency circuit. 

g. Usual method of providing a straight-control master circuit. 

h. Master control of a tw r o-location-controlled lamp-group by short-circuiting the 
switch travelers. 

i. An emergency circuit for two or more lamp-groups wherein one or more of the 
lamp-groups are provided with two-location control by two three-w r ay switches. In an 
installation where the two-location control is obtained by twm three-way switches, w r hat 
must be observed relative to the number of master-switch blades and master wires? 

j. Emergency circuit for two branches which serve a combination of one- and two- 
location-controlled lamps What types of switches will usually provide the more 
economical installation w r here a combination of one- and two-location-controlled 
lamps are connected to the same branch circuit. Illustrate by diagrams. 

k. An installation where only a part of the lamps are connected to the same branch 
circuit. 

l. An elementary universal-control master circuit. 

m. A universal emergency circuit for combined one- and two-location-control of 
lamps. 

n. Change the diagram of an ordinary wiring installation to one which is provided 
with a universal master circuit. 

o. Universal control of a master circuit for an installation containing multi-location 
control of lamp-groups by Carter-connected three- and four-way swatches. 

p. A combined Carter- and standard-connected installation provided with a master 
circuit. 

q. Control of a straight master circuit from two or more locations. Same for a 
universal master circuit. 

11. Wherein may two-location control of a master circuit be applicable? 

12. Name two methods of connecting the master switch into the side circuit of a 
three-wire system. Make a diagram to illustrate each. 


Sec. 2921 MASTER OR EMERGENCY CIRCUITS 243 


14. Explain with a diagram why unsatisfactory operation will result if the emergency 
circuit for a three-wire system is so arranged that the two side circuits are intercon¬ 
nected through the master wiring when the master switch is open. 

15. Draw a diagram to show why single-pole switches cannot be used to control each 
of two or more lamp-groups on the same branch circuit when a master circuit is provided. 
Explain. 

16. Draw a diagram to show how single-pole switches for the control of a lamp-group 
may be used in connection with a master circuit. What rules must be followed in such 
an installation? 

17. What should be done before an emergency-wiring installation is begun? Why? 


N 


DIVISION 7 


ELECTROLIER AND HEATER SWITCH CIRCUITS 

293. The Function Of An Electrolier Switch (see Sec. 53 for 
definition) is to provide varied control of several lamps or 
groups of lamps which may either be contained in the same 
fixture or else located at different points. Electrolier switches 
find their widest application for controlling lamps which are 
mounted in electrolier or dome fixtures; that is, in fixtures 
having, say, five lamps, two of which may be used regularly 
while the remaining three may be cut into the circuit to pro¬ 
vide either more light or an added ornamental effect. 

Note.—The Control Which Is Provided By An Electrolier 
Switch may be either: (1) Restricted. (2) Selective. (3) Restricted- 
selective (see Secs. 15, 16, and 17). The type of control which is pro¬ 
vided will depend upon the switch used. Switches which provide each 
of the above-mentioned controls are described in this division. 

294. Electrolier Switches May Be Classified According To 
The Number Of Circuits Which May Be Controlled, as: 

(1) Two-circuit electrolier switches. (2) Three-circuit electrolier 
switches. Electrolier switches are seldom made for the 
control of more than three circuits. The circuit-connections 
for both two- and three-circuit switches are described in 
following sections. 

Note.—Since Practically All Electrolier Switches Disconnect 
Only One Side Of The Line From The Source Of Voltage, They 
Must Be Considered As Single-pole Switches insofar as Code 
requirements (Secs. 141 to 144) are concerned. 

Note.—Practically All Electrolier Snap-switch Construction 
employs a mechanism which is of the revolving-blade type (Sec. 23). 
This mechanism may be operated by any of the following methods: 
(1) Rotating-button. (2) Push-button. (3) Pull-chain. (4) Toggle. See 
Secs. 29 to 32 for definitions. The principal forms in which electro¬ 
lier switches are made are: (1) Surface. (2) Flush. (3) Pendent. See 
Secs. 35 to 37 for definitions. 


244 


Sec. 295] 


ELECTROLIER SWITCH CIRCUITS 


245 


295. The Conventional Method Of Expressing The Circuit- 
connections Which Are Provided By An Electrolier Switch is 

by a series of numbers and words separated by dashes, as 
“1—2—1 & 2—Off.” As explained below, this convention 
may be used to indicate five different things concerning the 
switch: (1) The number of switch-positions. (2) The number 
of circuits controlled. (3) The lamp-groups which are lighted 
at each switch-position. (4) The lamp-groups which are extin¬ 
guished at each switch-position. (5) The sequence of lighting 
and extinguishing the various lamp-groups upon successive 
switch-handle operations. 

Explanation. —Assume that the control afforded by a certain electro¬ 
lier switch is expressed by “ 1—2—1 & 2—Off.” Since there are four 
groups which are separated by dashes, it is a four-position switch. 
The highest number used in the symbol is 2; therefore, it is a two-circuit 
switch; that is, two circuits or lamp-groups may be controlled by it. 
The figure or figures in each group indicate which lamp-group or lamp- 
groups are lighted for that switch-position. It should also be understood 
that the figure or figures which do not appear in any group indicate, for 
that switch-position, that the lamp-group of that number is extinguished. 
For example, the second group of the above expression contains only the 
figure “2.” That is, for this switch-position, lamp-group No. 2 is lighted, 
and since figure “1” does not appear in this figure-group, lamp-group 
No. 1 is extinguished. Also, since the figures “ 1 & 2” appear in the third 
group, both lamp-group Nos. 1 and 2 will, when the switch is in this 
position, be lighted. The word “off” indicates that when the switch is 
in that position, all lamp-groups are extinguished. The sequence of 
lighting and extinguishing of the lamp-groups for successive switch- 
handle operations is indicated by the sequence of the groups of numbers 
in the symbol. That is, “1—2—1 & 2—Off” indicates that if the 
switch is in the off-position, the first operation of the switch handle will 
light lamp-group No. 1; the second operation will light lamp-group No. 2 
and extinguish lamp-group No. 1; the third operation will light both 
lamp-groups; and the fourth operation will extinguish all lamps. 

296. A Three-position, Two-point Switch May Be Used As 
An Electrolier Switch as illustrated in Figs. 347 and 348. 
Figure 347 is an illustration of an actual installation employing 
a standard two-point fan-motor switch. The circuits, 1 and 
2, are completed by the movable contactor ( B , Fig. 347) 
bridging between a circular contact bar, D, in the base of the 
switch, and the stationary contactors, C i and C 2 . In this 
illustration, circuit No. 1 is operative; the current path being 


246 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 7 


from the point where the line, L 2 , attaches to the binding-post, 
P, which is electrically connected to the circular contact bar, 
D, from D through the movable contactor, B, to the stationary 
contactor, C 1 , thence through the lamp and into the line, L\. 



Fig. 347.—A three-position, two-point snap switch connected as an electrolier 
switch. (The ring contact bar, D, is sometimes called a circular bar.) (General Electric 
Company.) 


The circuit-connections for each of the three switch-positions 
are shown in Fig. 348. 


Note.—The Circuit Diagram For The Two-circuit, Three- 
position Electrolier Switch, as shown in Fig. 349, represents the same 
conditions which existed in the illustration of Fig. 347, with the exception 


..Two-Point Switch 



Lamp No. 2 

TPosition 1: LampNo.l,0n; Lamp No.2,0ff 



1-Position 2: Lamp No. 1, Off; LampNo.2,0n 



Lamp No. 2^^ 

HI* Position 3'. Both Lamps Off 



Lamp No. 2j pi 
Lamp\ No. 1 


Movable 
Contactor'' 

I*Position 1: Lamp No.l, On; 
Lamp No.2, Off 




Lme ^ 



'Lamp No. I 

I* Position 2: Lamp No. 1, Off; 
Lamp No.2, On 



Lamp No. r<2 

H*Position 3 - . Both Lamps Off 


Fig. 348. Fig. 349. 

Fig. 348.—Circuit diagram of the two-point swdtch which is shown in the preceding 
illustration connected as a two-circuit electrolier switch to provide restricted control 
of two lamps. (Arrows indicate the current-path.) 

Fig. 349.—Circuit-connections for a two-circuit three-position electrolier switch 
providing restricted control of two lamp-groups: “Lamp No. 1” represents one group 
and “Lamp No. 2” the other group. 


that the internal switch-connections which light the lamps are made in 
a somewhat different manner from that just described for Fig. 347. 























































Sec. 297] 


ELECTROLIER SWITCH CIRCUITS 


247 


As will be noted from the illustrations of I, II and III, (Fig. 349), the 
electrolier switch there diagrammed has three stationary contactors, or 
contact points: (1) Line contact, A. (2) Contact B for lamp No. 2. 
(3) Contact C for lamp No. 1 . The movable contactor, E, consists of a 
continuous copper strip forming two arms which are 120 mechanical 
degrees apart. 

It will be evident from the illustration of I, that as E bridges A and C, 
the circuit feeding lamp No. 1 is completed, and the lamp is lighted. 
At II, E bridges A and B. Therefore, lamp No. 2 of the second circuit is 
lighted. However, at this position of E, lamp No. 1 is extinguished. 
A third turn of the switch-handle throws the movable contactor to the 
position shown at III, so that it bridges B and C, and consequently, cuts 
out both lamps Nos. 1 and 2. The restricted control afforded by the 
switch is termed (Sec. 295) a “1—2—Off” combination. This type of 
switch finds frequent application in fan-motor circuits which require two 
speed controls. This switch may also be used (Sec. 311) to control a 
heating device. 

297. A Two-circuit, Three-position, Double-deck Electro¬ 
lier Switch is diagrammed in Fig. 350. The double-deck 
arrangement of the movable-contactors is shown in Fig. 351. 
Each of the movable contactors has two arms which are 



-©T- 

LampNo.Z-' 
\<-Lower Deck 

Lamp No.!-’' 

Branch Circuit- -X 


4 


I-Position I: Lamp No.I On. 

Lamp No.2. Off 



KLamp No. l-- : 
Lamp No.t-c, 


Branch Circuit-'X 


tt-Position l -Lamps Nos. 
I And 1 On 


UL-Posifion 3: All Off 


Fig. 350. —Circuits for two-circuit, three-position electrolier switch. (Switch 
contactors electrically connected.) This switch effects the same connections as does 
Bryant switch No. 2630. 


120 deg. apart. The upper- and lower-deck movable con¬ 
tactors are electrically connected. The current path is, for 
each of the switch-positions (Fig. 350), indicated by arrows. 
The sequence of the circuit connections is “1—1 & 2—Off.'’ 

Note.—The Symbolical Diagrams Which Are Used Herein lo 
Represent Multi-deck Snap-switches (Figs. 13-XA r , and Fig. 350) 
are^intended to obviate a confusion which might result if the upper- and 
lower-deck movable contactors were shown in a plan view as occupying 
positions one directly above the other. In the symbols in this book each 
deck of a multi-deck switch is shown as a complete and separate switch 
with its respective movable and stationary contactors. W r hen there is 



























248 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 7 


an electrical interconnection between the movable contactors, it is shown 
by a heavy vertical solid line which is drawn between the centers about 
which both the upper and lower movable contactors rotate. The 
dotted lines, which are tangent to the circumferences of the upper and 
lower decks, indicate that the two movable contactors are carried by the 
same shaft and mounted on the same switch base. Since the movable 
contactors of a multi-deck switch are carried by the same shaft, they 

rotate together, and consequently 
always occupy the same relative 
position with respect to each other. 
In the diagram of each deck, only 
the stationary and movable con¬ 
tactors of that deck are shown 
therein. If one binding-post car¬ 
ries two or more stationary con¬ 
tactors so that the stationary 
contactors in different decks are 
electrically connected, these two 
stationary contactors are connected 
by a heavy line as at A, Figs. 356-7 
and 361-7. 

Example. —In Fig. 350-7, the line, L x , connects to the stationary con¬ 
tactor, a, of the upper deck, and the current, as shown by the arrow, 
flows through the upper-deck movable contactor to the lower-deck 
movable contactor, thereby bridging stationary contactors a and c. 
Hence, lamp No. 1 is lighted. If the switch is in the position at 7, one 
operation will result in 77. It will then be noted (Fig. 350-77) that 
stationary contactors a and 6, which are in the upper deck, are bridged b} r 
the upper-deck movable contactor, thus resulting in lamp No. 2 being 
lighted. And at the same time, current passes through the upper- 
deck movable contactor to the lower-deck movable contactor— bridg¬ 
ing a and c —thus lighting lamp No. 1. Therefore, when the switch 
is in the position shown at 77, both lamps are lighted. The next opera¬ 
tion of the switch disconnects the circuit of both lamps Nos. 1 and 2 in a 
manner which will be evident from a study of 777. Obviously, the next 
operation of the switch will return both the upper and the lower movable 
contactors to the positions which they occupy in 7. 

298. A Two-circuit, Four-position Electrolier Switch of 

single-deck construction is illustrated in Fig. 352. The con¬ 
tactor-arrangement, and the circuit-connections provided by 
the four different switch-positions may be understood by refer¬ 
ence to Fig. 353. As indicated in Fig. 353, the following 
combinations are obtainable: (1) Lamp No. 1, on; and lamp 
No. 2, off. (2) Lamp No. 2, on; and lamp No. 1, off. (3) Both 


Rivets Shaft-■> 



Contact 
Jaws . 


Upper-Deck 

Movable 

Contactor 


'Lower-Deck Movable Contactor 

Fig. 351.—Showing an upper and lower- 
deck arrangement of the movable con¬ 
tactors in a two-circuit three-position elec¬ 
trolier switch. 















Sec. 299] 


ELECTROLIER SWITCH CIRCUITS 


249 


lamps on. (4) Both lamps off. Therefore, selective control 
(Sec. 16) is provided. Such circuit-connection sequence is 
conventionally expressed as: “ 1—2—1 & 2—Off. ” A lighting- 
and-extinguishing sequence different from that in Fig. 353 
may be obtained with the same switch (Fig. 352) by changing 



Fig. 352.—Wiring diagram of two-circuit, four-position electrolier snap switch. (Selec¬ 
tive control is provided. General Electric Co.) 

the connection of the switch feed wire from a, Figs. 352 and 
353 -I, to h Fig. 354, and by changing the connections of the 
return wires of circuits Nos. 1 and 2 respectively, from c and 
b, Fig. 352, to a and c, Fig. 354. The same control—selective 
—is provided in Fig. 354 as in Fig. 353. However, the 



I-Posi+ionl: Lampl.On; Lamp 2. Off 1-Position 2: Lamp?,On; Lampl.Off 



Fig. 353.—Circuit-connections for two-circuit, four-position electrolier snap switch. 
(Selective control of the following sequence is provided: “1—2—1 & 2—Off.”) 

sequence of circuit-connections as shown in Fig. 354 is “1— 
1 & 2—2— Oft.” The arrows indicate the current-paths. 

299. Other Circuit-connections For Two-circuit, Four- 
position Electrolier Switches are shown in Figs. 355, 356 and 
357. The shapes of the upper and lower movable contactors 

















































250 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 7 


Switch Feed Wire ' •^■ ■Orou p 2 
Lamp : 



Group 2...y > 



I-Posit ion 1: Group 1 On, 
Group 2 Off. 

Group 2-..OQ., 
=5^ 



HPosition 2: Groups 1 And 2 On. 

Group 2-... J0, 


-Q" 

J rv-d Group 
Line\ | 1 

■€> : 


jE-Posi+ion 3: Group 2 On, 

Group 1 Off. 


Electro lien, 
Switch 


p- Line 



W' 

)) Group 


I? Position 4: All Off. 


Fig. 354.—Circuit-connections for two-circuit, four-position electrolier switch. 
(Selective control is provided: “1—1 & 2—2—Off.” This switch effects the same con¬ 
nections as does Bryant switch No. 2625.) 


.e ^roup /- 




L 


vTTT 'O 4 

j Upper Deck 


Group 


jr 


! 


---Liqe 





^ Group /-— 
A-Lower Deck 
| Group 2--.^ -q. ■ 


I-Position !: Group I, On. Group 1 , Off. 1-Position 1 -Groups I And 1 On 


. > 




[Group I— 

Group 2----^fcr 


1 -G- 


E-Position 3:Group I,On. Group 2,Off 


H-Position 4: All Off 


Fig. 355. —Circuit connections for two-circuit, four-position electrolier switch. 
(Restricted-selective control: ‘‘1—1 & 2—1—Off.” This switch effects the same con¬ 
nections as does Bryant switch No. 2626.) 


Upper 
Deck-'' pA 



Group 2- 






O 1 . | 


Lower 



Deck-. 


; r 
| Grow/? 2—^ ^' 

]Group A 


1-Position l - .Group l,On. Group 2, Off E-Position 2: All Off 



Group Z---^ 
Group 



Group Z--? r 'Ck' 
Group /•-. 


E-Position 3: Group 2,On. Group I, Off EZ-Position 4: All Off 


Fig. 356. —Circuit-connections for two-circuit, four-position electrolier switch. 
(Restricted control, ‘‘1—Off—2—Off.” This switch effects the same connections 
as does Bryant switch No. 2628.) 






























































































































































Sec. 300] 


ELECTROLIER SWITCH CIRCUITS 


251 


of these double-deck switches are indicated in the respective 
illustrations. The control which is provided by each of these 
switches when connected as shown, is as follows: Fig. 355, 
restricted-selective, “1—1 & 2—1—Off;” Fig. 356, restricted, 
“1—Off—2—Off;” Fig. 357, restricted-selective, “1 —Off—1 
& 2—Off. The current-paths for each switch-position is 
indicated by the arrows. 



I- Position 1: Group! On. Group 2,0ff 



HI* Position 3: Groups 1 And 2 On 



H-Position 2: All Off 




Croup i-- , 


1 


' 



- 

U. 

I 

i \ Croup ?' x 



i Lower Snitch Contactor 

Li 




TJ-Position 4: All Off 


Fig. 357.—Circuit-connections for two-circuit, four-position electrolier switch. 
Restricted-selective control: “1—Off—1&2—Off.” (This switch effects the same con¬ 
nections as does Bryant switch No. 2629.) 


Note. —A Combination Of Two Single-pole Switches Mounted 
Within The Same Porcelain Casing And Having A Common Feed 
(Fig. 68) is illustrated in Fig. 358. The movable contactor of each of 
these single-pole switches (Sec. 90) is actuated by a separate push-button 
ratchet-gear mechanism (Sec. 89). As will be noted from the diagrams 
shown in Fig. 358, such a switch can be used for the control of two 
circuits. At /, the lamp, A, is connected to the line as indicated by the 
arrows. If the push button controlling this circuit containing lamp A 
is operated, the lamp will be extinguished. To light the lamps of group 
B, it is necessary to throw the switch controlling the first circuit to the 
on position and then to throw the switch controlling the second circuit 
to the on position, as at II, Fig. 358. This switch provides a “1—1 & 
2 —Off” control combination. See also Fig. 102-XF, and Sec. 182. 

300. A Three-point Fan-motor Switch May Be Used As A 
Three-circuit Electrolier Switch as illustrated in Figs. 359 
and 360. The circuit-connections of such an installation 
provide (Fig. 360) restricted control of three separate circuits, 
the sequence of connections being 11 1 —2—3—Off.” There¬ 
fore, such a switch finds frequent applications for those 


























































252 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 7 


installations where it is desired that only one of three lamps 
may be lighted at one time. The construction of the three- 
point switch of Fig. 359 is similar to that of Fig. 347, which is 
described in Sec. 296. 


.-Duplex Snitch 



1-Lamp A, On. Group B, Off 


Y - 

.- ‘Dup/ex’Snitch 


') Return Wires Lamp J|Tj 

Group B-j NjA 1 

s- V - 


l 

Lamp-Feed Wire | 



I- Lamp A And Group B On 


...-Snitch-Feed Wire 
v 

Return Wires 






Lamp '^ 


Lamp-Feed Wire 


Group B > 


H- Lamp A And Group B Off 


Fig. 358.—Two single-pole switches having a common feed used as two-circuit electro¬ 
lier switch provide a “1—1 & 2—Off” control. 


301. Probably The Most Generally-used Three-circuit 
Electrolier Switch Is A Four-position, Double-deck Switch 

which provides a restricted-selective control of the sequence 



Fig. 359.—Three-point fan-motor switch used as an electrolier switch. (Restricted 
t control_of 4 the sequence: ‘‘1—2—3—Off,” is provided. General Electric Co.) 

“1—1 & 2—1 & 2 & 3—Off.” The circuit-connections are 
shown in Fig. 361. For wiring diagram of such a switch, see 
Fig. 102- XI. The current-paths for each of the four differ- 
ent switch-positions (Fig. 361) are indicated by the arrows. 



























































Sec. 301] 


ELECTROLIER SWITCH CIRCUITS 


253 



I-Position 1: Lamp No. 1 On; H-Position 2: Lamp No. 2 On; 

Lamps Nos. 2 And 3, Off Lamps Nos. 1 And 3, Off 



Fig. 360. —Circuit connections of a three-point switch used as a three-circuit electrolier 
switch to provide restricted control of the sequence: ‘ 1 2 3 Off. 


■ Upper Deck 


■-■Lamp No. 1 Upper Deck- 



Lamp Feed 
Wire 

L Lamp No. 2 
]< Lower Deck 



'•'■<■ Lamp No. 2 
H Lower Deck 


I-Position 1: Lamp No.lOn. 
Lamps Nos. 2 And 3 Off 

.. Upper Deck 


I-Position 2: Lamps Nos.l And 
? On. Lamp No. 3 Off 

Upper^ Deck _ Lam p No.l 



H-Posit ion 3: All Lamps On 


ET-Position 4: All Lamps Off 


Fig. 361—Circuit-connections of three-circuit, four-position electrolier switch providing 
• • i j & 2 1 & 2 & 3—Off” control. (List No. 2627, Bryant Electric Co.) 





















































































254 


LIGHTING CIRCUITS AND SWITCHES 


[Drv. 7 


This switch is made both in the rotating-button, and pull-chain 
surface forms, and in the push-button flush and pendent forms. 






Fig. 362. —Illustrating internal circuits of “Duplex” switch. (Bryant Electric Co 

List No. 2640.) 



Fig. 363. —Duplex switch consisting of a three-circuit, three-position electrolier 
switch in series with a single-pole switch. Electrolier switch provides following se¬ 
quence of control: 1—2 & 2—1 & 2 & 3. (Bryant Electric Co., List No. 2640.) 


302. A Combination Of A Single-pole Switch With An 
Electrolier Switch Which Has No Off Position is shown in 
Fig. 362. As shown in Fig. 363 the single-pole switch is con- 











































































































































Sec. 302J 


ELECTROLIER SWITCH CIRCUITS 


255 


nected in series with the electrolier switch. The three-position, 
three-circuit electrolier switch, which is of the double-deck 
type, provides the following control: 1—1 & 2—1 & 2 & 3. 
Since the single-pole switch is in series with, and may be oper- 


■ Upper Deck 



Fig. 364.—Duplex switch consisting of a single-pole switch in series with a three- 
circuit, four-position electrolier switch which provides the following control: 1—2—3— 
1 & 2 & 3. (Opening S, as indicated by the dotted position in IV will at any time 
extinguish all lamps. List No. 2744, Bryant Electric Co.) 

ated independently of the electrolier switch, all of the lamps 
may, at any time, be extinguished (Fig. 363 -IV) by opening the 
single-pole switch. Thus, in reality, the combination provides 






























































256 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 7 


the following control: 1—Off—1 & 2—Off—1 & 2 & 3 Off. 
The circuit connections for certain other combined single-pole 
and electrolier switches are shown in Figs. 364 and 365. The 
arrows indicate current-paths. See also Fig. 102 -XVI and 
XXII. 



I-Position l: Lamp No.l.On; 
Lamps Nos. 2 And 3, Off 



H-Position 3 - . Lamps Nos.l And 
3, On; Lamp No. 2 Off 



JI-Position 2: Lamps Nos.l And On; 


Lamp No. 3. Off 



17-Position A\ All Lamps On 


Fig. 365.—Duplex switch consisting of a single-pole switch in series with a three- 
circuit, four-position electrolier switch which provides the following control: 1—1 & 2— 
1 & 3—1 & 2 & 3. (With the electrolier switch in any position, opening the single¬ 
pole switch will extinguish all lamps. Bryant Electric Co., List No. 2745.) 


303. A Three-circuit Electrolier Switch Wired In Conjunc¬ 
tion With Two Three-way Switches And One Four-way 
Switch is illustrated in Fig. 366. An actual installation which 
employs the same circuit connections is shown in Fig. 367. 
The three-way switches, Ti and T 2 , together with the four-way 
switch F, provide three-location control for lamp A, and if 
the electrolier switch, E, is in either of the closed positions, 
three-location control is also provided for the electrolier lamps. 
Since the electrolier switch, E , is connected into the circuit 

























































Sec. 303] 


ELECTROLIER SWITCH CIRCUITS 


257 


ahead of 7\, T 2 , and F, none of the electrolier lamps can be 
lighted without also lighting A . Also, if E is in the off posi- 


<•- 


Li 


Fig. 366. 


Switch- 

Feed 

Wire-., 


■ Three-Way Switch In 
Second Floor Hall 


Three- Way Switch 
In First Floor Hall- 



Switch 


, - Four ■ Way Switch 
F (If Desired) 

F_ 

Switch Travelers 




Branch 

Circuit 




t Lamp-Feed 

Travelers 

cA 

p;Return Wires 


Wires 

■ o 2 

Ui 

> ~~i 

i/i 3 

■V 


Return Wire 

_ 

Chandelier Lamps, In First-Floor Hall 

j 


"Second Floor 
Hall Lamp 


Electrolier Switch Mounted In Gang 
With Three-Way Switch In First Floor Halt' 


-Electrolier switch wired in conjunction with three- and four-way switches. 
With switches m positions shown all lamps are off. 


tion, none of the chandelier lamps can be lighted by operating 
T i, T 2 , or F. Therefore, with such an installation, if three- 
location control of the up-stairs and down-stairs hall lamps is 



Fig. 367.—Illustrating an actual installation of electrolier switch wired in conjunction 

with three- and four-way switches. 


desired, the electrolier switch, E, must always be left in one of 
the closed positions. 

17 




































































































258 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 7 


304. A Method Of Obtaining Multi-location Control Of 
Lamps Which Are In Turn Controlled By An Electrolier 
Switch is illustrated in Fig. 368. The electrolier switch, E, 

which has no off position, is 
mounted in gang with the 
three-way switch T\. This 
combination provides one 
control location. The three- 
way switch, T 2 , provides 
another control location. Ad¬ 
ditional control locations may 
be obtained by connecting 
four-way switches into the 
,a"p:\vht^^“t/rd r tat switch traVelerS as suggested 

electrolier switch which has no off position, in Fig. 253. 



Explanation. —The electrolier switch, E, Fig. 368 is identical with the 
electrolier switch, E, Fig. 363. Thus, the control sequence provided by 
E (Fig. 368) is: 1—1 & 2—1 & 2 & 3. Hence if a person is at the ETi- 
location, he may by means of E, select either of the three available 
lamp-group combinations (Fig. 363-7, II, or III), and then light the 
combination which was selected by 
T\. Since in this particular switch 
(E, Fig. 368), lamp-group No. 1 is 
(Fig. 363) always connected into the 
circuit, it may be desirable to install 
two lamps (A and B, Fig. 368) in this 
group. Then by locating a three-lamp 
fixture—consisting of lamps 2, 3, and 
A of group 1—and switches E and 
in the lower hallway, and lamp B and 
switch T 2 in the upper hallway, both 
hallways can then be lighted from 
either the up-stairs or down-stairs 
switch location. 

305. One Or More Lamps 
Of An Electrolier-switch- 
controlled Multi-lamp Fixture 
May Be Connected To An 
Emergency Circuit (Div. 6) by one of the following methods: (1) 
By directly connecting the lamp to the master wire, as at L, Fig. 
320. (2) By connecting one or more lamps of the fixture to a 



Fig. 369. —An electrolier switch which 
has no off position connected in series 
with a three-way switch for use in con¬ 
junction with an emergency circuit. 
(With the master switch closed, one or 
other of the combinations, as outlined 
in Fig. 361 will always be lighted. 
With the master switch open, any com¬ 
bination may be extinguished by T.) 





































Sec. 30G] 


ELECTROLIER SWITCH CIRCUITS 


259 


separate three-way switch , Fig. 319. (3) By connecting a 

three-way switch in series with a “ no off-position” electrolier 
switch, which might be made as shown in Fig. 369. (4) By 

the use of a special switch , as explained below. Connecting a 
lamp directly to the master circuit may, since the lamp will 
only be lighted when the master switch is closed, be objection¬ 
able from the standpoint of appearance. Although the 
methods which are outlined above in (2) and (3) eliminate any 
objection as to appearance, the use of the additional three-way 
switch may add materially to the installation cost. 

Explanation. — A Special Electrolier Switch, E, For Use With 
A Master Circuit, might be arranged as shown in Fig. 370; this is a 
double-deck switch, the upper deck of which is identical to that of the 



Fig. 370.—Special electrolier switch for use with an emergency circuit. 


single-deck switch of Fig. 353. Therefore, the control provided is: 
1—2—1 & 2—Off. But when the switch (E, Fig. 370) is in the off 
position, the movable contactor of the lower deck then connects the 
three lamps, A, B, and C, to the master wire, W, of the master circuit. 
Also this is the only position wherein A, B or C will be connected to W. 
Therefore, if the master switch, M, is closed when the upper-deck mov¬ 
able contactor is in the open position, A, B and C will then be lighted, the 
current path being as indicated by the arrows. With any other position 
of E , the lamps will be lighted through F as indicated in Fig. 353. 

306. The Term '‘Heater Switch” is usually applied to those 
snap switches which are so designed that by successive opera¬ 
tions of the switch handle, two elements—coils or resistors— 
of a heating device may, in addition to disconnecting the 
elements from the supply circuit, do one or more of the following: 
(1) Connect only one coil to the supply circuit. (2) Connect the 

























260 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 7 


two coils in parallel to the supply circuit. (3) Connect the two 
coils in series to the supply circuit. Although a switch of any 
type, such as an ordinary single-pole switch, a double-pole 
switch, a three-way switch, or the like, may be used for the 
control of heating devices, they are not, even when so used, 
generally termed heater switches. 

Note.—The Single- And Double-pole Switch Circuits Which 
Were Described As Dimmer Circuits (Div. 4) may be used as heater 
switches by substituting a resistor or heating element for each lamp- 
group. 

Note.—Any Switch May Be Used As A Heater Switch If Its 
Approved Capacity Is Not Exceeded. The ratings of those snap 
switches which are, in the trade, called heater switches, vary from 10 
amp. at 125 volts (1,250 watts) up to 35 amp. at 250 volts (8,750 watts). 

307. The General Requirements Which Are Necessary For 
The Successful Operation Of Heater Snap Switches are: 

(1) Sufficient current-carrying capacity. (2) Sufficient 
movable contactor speed to prevent a dangerous arc upon make 
and break. (3) Ability to withstand a high temperature. The 
problems of current-carrying capacity and of make-and-break 
action cannot be determined by sight or theory. The switch 
either operates successfully or it does not. However, all approved 
(Sec. 115) heater switches are tested, and will usually operate 
satisfactorily if their rated load is not exceeded. Sometimes 
the switches on electric ranges and other heating devices are 
mounted too close to the heating elements, or sufficient heat- 
insulation from the heating elements is not provided. Under 
such conditions, switch failure may be due to the heat which is 
transmitted from the heating elements. 

308. Heater Switches Must Be Of A Type Which Will 
Plainly Indicate Whether The Device Controlled Is “On” Or 
“Off” (Sec. 150).—In heater switches of the surface type (Fig. 
371), this indication is usually provided by the words “Off,” 
“High,” “Medium” and “Low” (see explanation below), 
arranged as suggested in Sec. 114. When a plug connection 
(Sec. 150) is used for a heater circuit, the indication may be 
provided by a combination receptacle—pilot lamp and 
switch—(Fig. 372) which is so wired that when the switch is 
closed, the pilot lamp will be lighted. 


Sec. 308 ] 


ELECTROLIER SWITCH CIRCUITS 


261 


Explanation.—The Words “Off,” “High,” “Medium,” And 
1 L° w ” As Applied To Heater-switch Indications merely indicate 
the comparative amount of heat which will be emitted by the heating 
device when the switch is in the respective positions. That is, if a 



Porcelain 

Base--'' 


Fig. 371. 



--Base 


■ Plug Receptacle 

Double-Pole 
Switch 


Fig. 372. 


Fig. 371.—Surface type heater switch showing method of indicating whether the 
current is off or on. (The current is on when the pointed-button points to ‘High,” 
‘Low,” or Med.” Bryant Electric Co., List No. 2801.) 

Fig. 372.—-Ready-wired surface-type heater-control combination receptacle, switch, 
and indicating lamp. (The pilot lamp is wired in parallel with the receptacle so that 
the lamp is lighted when the switch is closed. Bryant Electric Co., List No. 466.) 


heater switch (Fig. 373), the operating sequence of which is off, high, 
medium and low, controls two equal-capacity heating elements, A and 
B, of a heating device, no current will flow when the switch is in the off 



Fig. 373.—Illustrating the meaning of heater-switch indications. (Dotted lines 
indicate the connection which are made inside of the switch. Arrows indicate current 
paths. (Bryant Electric Co., List No. 2619.) 


position. When the switch indicates “high” (Fig. 373-/7), A and B are 
in parallel. When the switch indicates “medium” (Fig. 373 -III), 
only one element, as A, is on, and the other element is off. When “low” 
is indicated (IV), the two elements are in series. 






















































































































262 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 7 


Consider two heating elements, which are alike in every respect and 
in which there is no change in resistance with a temperature change. 
Now assume that the two elements will, when connected in series to a 
given source of voltage (Fig. 373-7 V) give off one heat unit. Then, one 
of the elements, when connected to the same source (III), will give off 
two heat units. And if the two elements are connected in parallel (Fig. 
373-/7) to the same source of voltage, four heat units will be emitted. 
If the two elements are unlike in shape or are of unequal resistances the 
above proportions do not hold. 

309. Heater Switches Are For Use On Heating Devices 
Which Have Two Heating Elements —coils or resistors—in 
each unit such as cooking devices, radiators, mangles, indus¬ 
trial heaters for glue-pots, linotype metal, and the like. As 
suggested in Sec. 306, ordinary single-pole or double-pole 
switches, such as those which are generally used for lighting- 
circuits, may be used to control heating devices which have 
only one heating element in each unit. Hence, such switches 
may be used for flat irons, toasters, curling irons, water 
heaters and the like. Various types of heater switches and the 
circuit-connections which are effected thereby are treated in 
the following sections. For methods of installations, see the 
author’s Wiring For Light And Power. 

310. Heater Switches May Be Classified According To 
The Circuit-connections which are made as: (1) A series switch , 
Fig. 374, whereby the two heating elements may, by successive 



I-Position l:“Low“ 
A And B In Series 



H-Position 2'."High" 
B, On. A. Off 


H-Position 3: Off 


Fig. 374. —Single-pole series heater switch providing the following sequence of con¬ 
nections: “Low—High—Off.” 


operations of the switch handle, first be connected across the 
line in series, then only one element connected across the line, 
then both elements disconnected from the line. (2) A parallel 
switch, Fig. 376, whereby the two heating elements may, by 
successive operations of the switch handle, first be connected 
across the line in parallel, then only one element connected 









Sec. 311] 


ELECTROLIER SWITCH CIRCUITS 


263 


across the line, then neither element connected to the line. 
(3) A series-parallel switch , Fig. 382, whereby the two heating 
elements may, by successive operations of the switch handle, 
first be connected across the line in parallel, then across the 
line in series, then only one connected across the line, then 
neither connected to the line. The series and parallel heater 
switches are usually of the single-pole type, whereas the series- 
parallel switches are regularly manufactured in both the 
single- and double-pole types. Circuit connections of switches 
of each of the above classifications are described in the follow¬ 
ing sections. 

311. The Circuit-connections For A Single-pole Series 
Heater Switch are diagrammed in Fig. 374. As indicated, 
it is a three-position, single-deck switch. When connected 
to control two heating elements, as shown in Fig. 374, the 



I- Position 1: “High" B, I-Position 2: “Low" A HI* Position 3/Off ” 
On And A. Off And B In Series 


Fig. 375.—Single-pole series heater switch which provides the following sequence of 

connections: “High—Low—Off.” 

sequence of operation is: “Low—High—Off.” By inter¬ 
changing the connections C and D of Fig. 374, the sequence of 
operation (Fig. 375) will be: “High—Low—Off.” The cir¬ 
cuit-connections which are provided by a heater switch such 
as that shown in Figs. 374 and 375 are the same as those which 
are provided by the electrolier switch in Fig. 349. Such a 
switch, if of suitable capacity, may be used either to control a 
heater unit or to control two lamp-groups. 

Note—The Kind Of Apparatus Which A Switch Controls 
Sometimes Governs The Name Which Is Applied To The Switch. 
if a switch such as that described above is used to control lamps, it 
is usually called an electrolier switch. And the same switch, if used to 
control a heating device, is then ordinarily called a heater switch. 

312. The Circuit-connections For A Single-pole, Parallel 
Heater Switch are shown in Fig. 376. It is a single-deck, four- 















264 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 7 


position switch. When connected as shown in Fig. 376 to 
control two heating elements, A and B, of unequal capacity, 
successive operations of the switch so connect the heating 
elements to provide the following sequence: "Low—Medium 


.Heater Switch 



*wir—It L 

Heating, ' 


1 


A 2 .. 

Elements 


I" Position 1: “Low.” A On. And B Off 



H-Position 2: Medium? A Off. And B On 



A 1 

•wuituippJ 




H~ Posit ion 3: “High’.' A And B In Parallel TZ*Position 4‘. Off” 


qruirmnjip 

A 


Fig. 376.—Single-pole parallel heater switch controlling a unit consisting of two 
heating elements of unequal capacity. (As connected the following sequence of heating 
effects are provided: “Low—Medium—High—Off.” (Bryant Electric Co., List No. 
2216, 10 amp. at 125 volts or 5 amp. at 250 volts; that is 1250 watts.) 


—High—Off.” If A and B are of equal capacity, only two 
heating effects—“High” and “Low”—will be provided (see 
explanation below). This switch is identical to that shown 
in Fig. 353, and (Sec. 298) may be used either as a heater 


.- Heater Switch 




H'Position 3: High”; A And B In Parallel E7- Position 4: "Off" 


Fig. 377. Single-pole parallel heater switch controlling two elements of unequal 
capacity. As connected the following sequence of heating effects is provided- “ Medium 
—Low—High—Off.” 


switch or as an electrolier switch. If the connections of the 
line, L, and the heating elements, B and A, are changed from 
binding-posts 1, 2, and 3, as shown in Fig. 376, to 1, 3, and 2, 
as shown in Fig. 377, the operating sequence will then be: 
“Medium Low—High—Off.” The other possible changes 















































Sec. 312] ELECTROLIER SWITCH CIRCUITS 265 

which may be made in the external connections, and the 
operating sequence which results therefrom are shown in 
Figs. 378, 379, 380 and 381. 

Explanation. Since element B (Fig. 376) has a lower resistance 
than A, more current will flow (Fig. 376-/7) through B than will flow 
through A (Fig. 376-7). In 777, the two elements are in parallel. This 



T 

A> 

c 

* V* 

'll 



-Heater 5witch 


B 

- —^ITlflr *— 1 

/ A 

hfljmnnnrb* 

Heating f 
Elements *' 


Fig. 378.—Single-pole parallel heater 
switch, controlling two heating elements 
of unequal capacity, which is connected to 
operate “ High—Low—Medium—Off.” 


Fig. 379.—Single-pole, parallel heater 
switch controlling two heating elements 
of unequal capacities. (The switch, as 
connected operates: ‘‘High—Medium— 
Low—Off.” 


still further decreases the resistance of the unit, thereby developing more 
heat than in either 7 or 77. Hence, by using such a switch with a unit 
which consists of two unequal-capacity elements, three different “heats” 
are provided. If the elements were of the same capacity, the amount 
of heat given off by 7 would be equal to that given off by 77, then only 
two “heats” would be available. 




Fig. 380.—Single-pole, parallel heater 
switch controlling two heating elements 
of unequal capacities. (When connected 
as shown, the switch operates: ‘‘Low— 
High—Medium—Off.” 


Fig. 381.—Single-pole, parallel heater 
switch controlling two heating elements 
of unequal capacities. (As connected, 
the switch operates: “Medium—High— 
Low—Off.”) 


Note.—The Binding-posts, Or Terminals, Of Practically All 
Snap Switches Are Marked To Indicate How The Switch Should 
Be Connected. This marking, which is usually stamped on the 
porcelain, corresponds to the marking on the diagram of connections 
(Figs. 101, 102, 103 and 104), which will be furnished by the manufacturer 
of the switch. If the markings on the switch have been defaced, or if 
the diagram of connections is not available, the wireman should, if 
possible before connecting up the switch, carefully trace out the internal 
connections for each switch position. Otherwise, trouble is likely to 
result. Also, if the connections to a heater switch are, for the purpose 


























266 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 7 


of changing the operating sequence, changed from that which is indi¬ 
cated on the porcelain, the wirernan should, by carefully tracing out the 
internal switch connections for each switch position, first determine 
whether or not the switch will operate under the changed connections. 
If it will operate successfully with the connections changed, the indicator 
should then be altered to correspond with the new operating sequence. 

313. The Circuit-connections For A Single-pole, Series- 
parallel Heater Switch are diagrammed in Fig. 382. This 
four-position switch, when connected to control a heating 
device which has two equal-capacity heating elements, oper- 






Fig. 382.—Circuit-connections of a single-pole series-parallel heater switch controlling 
two heating elements of equal capacity which operates: “High—Medium—Low—Off." 
(Bryant Electric Co., List No. 2619.) 


ates: “High—Medium—Low—Off.” See Fig. 104 -XIV for 
wiring diagram. The switch which is diagrammed in Fig. 
383 is similar to that in Fig. 382. However, the movable- 
and-stationary-contactor arrangement of Fig. 383 control the 
heating elements to operate: “Low—Medium—High—Off.” 

314. The Circuit-connections For A Double-pole, Double¬ 
deck, Four-position, Series-parallel Heater Switch are shown 
in Fig. 384. This switch, when connected as shown to control 
a heating device which has two equal-capacity heating ele¬ 
ments, operates: “High—Low—Medium—Off.” When in 











































Sec. 314] 


ELECTROLIER SWITCH CIRCUITS 


267 



Fig. 383. —Circuit-connections of a single-pole, series-parallel heater switch controll¬ 
ing two heating elements of equal capacity. (The switch operates “Low—Medium— 

High—Off ’’) 



Fig. 384. —Circuit-connections of a double-pole, series-parallel heater switch controll¬ 
ing two equal-capacity heating elements, A and B, which operates “High—Medium— 
low—Off.’’ (Bryant Electric Co., List No. 2800.) 




























































































































268 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 7 


the off position (Fig. 384-7 V), all wires of the heating ele¬ 
ments are disconnected from the line. It is therefore a 
double-pole switch and may be used on devices which have a 
capacity (Sec. 150) above that required for single-pole heater 
switches. This switch is approved for 30 amp. at 125 volts, 
or 15 amp. at 250 volts, that is, for 3,750 watts. See Fig. 104- 
XIII for wiring diagram. 

QUESTIONS ON DIVISION 7 

1. What is the function of an electrolier switch? 

2. What applications are made of electrolier switches? 

3. Name and define the three types of controls which may be obtained with electro¬ 
lier switches. 

4. Classify electrolier switches according to the number of circuits controlled. 

5. What is the maximum number of circuits for which electrolier switches, as 
generally manufactured, will control? 

6. Why are electrolier switches considered as single-pole switches insofar as Code 
requirements are concerned? 

7. In general, what are the methods of operation and the forms of electrolier switches? 

8 . What is the conventional method of expressing the circuit-connections which are 
provided by an electrolier switch? 

9. What is meant by the expression, “l—2—1&2&3—Off,” as applied to 
electrolier switches? 

10. Give five facts about the switch which such an expression indicates. 

11. Show by sketch how a three-position, two-point, fan-motor switch may be used 
as an electrolier switch. Make a circuit diagram for each of the three positions. 

12. Make a sketch of the circuit-connections of a two-circuit, three-position electrolier 
switch for each of the three positions. 

13. Make sketches of the circuit-connections of three different two-circuit electrolier 
switches; one to provide selective control; one to provide restricted control; and one 
to provide restricted-selective control. 

14. Make a sketch to show how two single-pole switches having a common feed may 
be used as an electrolier switch. 

15. Show by sketch how a three-point, fan-motor switch may be used as a three circuit 
electrolier switch. 

16. Make a sketch of the circuit-connections for each position of a three-circuit, 
four-position electrolier switch. 

17. Show by sketch how multi-location control of lamps which are in turn controlled 
by an electrolier switch may be obtained. 

18. Name and explain by diagram four methods in which an electrolier-switch- 
controlled lamp-group may be connected to a master circuit. What are the advantages 
and disadvantages of each method? 

19. What is a heater switch? 

20. How may a single- or a double-pole switch be used as a heater switch. Explain 
by sketch. 

21. Give the capacity range within which heater switches of the snap type are gener¬ 
ally manufactured. 

22. What are the requirements for the successful operation of heater snap-switches? 

23. Why should a heater switch be protected from the heat of the heating device 
which it controls? 

24. How may a heater switch be made indicating? 

25. How may a heater outlet be made indicating? 

26. Explain the meaning of the terms, “High,” “Low,” “Medium,” and “Off,’ 
asjused on indicating heater switches. 


Sec. 314] 


ELECTROLIER SWITCH CIRCUITS 


269 


27. What are the relative amounts of heat which will be emitted by two similar heating 
elements when connected in series across the line, when only one element is across the 
line, and when the two elements are in parallel across the line? Does this relation hold 
if the two elements are dissimilar? 

28. Where are heater switches frequently used? 

29. Classify heater switches according to the circuit-connections which may be 
effected by them. 

30. What is meant by the terms: (a) Series switch. ( b) Parallel switch, (c) Series- 
parallel switch? Make a sketch of each. 

31. Make a sketch of the circuit-connections for: (a) A single-pole, series heater 
switch. ( b ) A single-pole, parallel heater switch. (c) A single-pole, series-parallel heater 
switch. ( d ) A double-pole, series-parallel heater switch. 

32. What may sometimes govern the name which is applied to a switch? Give an 
example. 

33. Show by sketch how the control-sequence of a heater switch may be changed by 
merely changing the wires from one binding-post to another. 

34. How are the terminals of all snap-switches generally marked. 

35. What should always be done before connecting up a snap switch? 


DIVISION 8 


REMOTE-CONTROLLED, DOOR, AND TIME SWITCH 

CIRCUITS 


315. A Remote-controlled Switch is a switch which may be 
operated electrically from a distance by closing or opening a 
control circuit (Sec. 316) which extends through one or more 
electromagnets. The electromagnets form a part of and are 
mounted on the switch. A remote-controlled switch is some¬ 
times called a remote control switch or a remote switch; also a 
magnet switch. 

Example. —A Diagram To Illustrate The Definition Of A 
Remote-controlled Switch is shown in Fig. 385. At /, the remote- 
controlled switch, R, is open. By closing the single-pole switch, S, 
current flows through the electromagnet, M, as indicated by the light 




Lamps-■' 


Electromagnet- 


Con factor-- 


< - -Remote- Controlled 
Switch 


,;r 

I-Switch Open H-Switch Closed 

Fig. 385. —Illustrating definition of remote-controlled switch. 


■Single-Pole Switch Af Considerable Dis 
From Remote-Controlled Switch 


arrows in II. This current energizes M, thereby pulling the contactor, 
P, upward to the closed position. Current may then flow through the 
lamp circuit, as indicated by the heavy arrows, thus lighting the lamps. 
As long as S is closed, M remains energized, and P is held in the closed 
position. If S is opened, the electromagnetic force on P is removed, and 
P falls by gravity Thus, R is opened and the lamps are extinguished. 

Note.—Theoretically, A Remote-controlled Switch May Be 
Remotely Controlled Either Mechanically Or Electrically. 
Switches which are used for the control of high-voltage circuits are 
frequently provided with a system of links and levers so that the switch 
may be manually operated by a handle which may be located several or 
many feet away from the switch mechanism. Such a switch is truly a 

270 





























Sec. 316] 


REMOTE-CONTROLLED CIRCUITS 


271 


remote-controlled switch, in the sense that it may be operated from a 
location which is remote from the switch. However, in this book most 
of the remote controlled switches which will be considered are electrically 
remote controlled. Hence, herein, unless otherwise specified the term 
“remote-controlled switch” will ordinarily mean an electrically remote- 
controlled switch. 

316. Remote-controlled Switches Have Two Separate 
Circuits: (1) The control , or operating circuit , Sec. 328. (2) 
The load circuit which is the circuit which serves the electrical 
load and which is controlled by the opening and closing of the 
remote-controlled switch. Each of these circuits are treated 
subsequently, starting with Sec. 328. 

317. Remote-controlled Switches Are Used to control both 
lighting and power circuits. The principal use of remote- 
controlled switches for lighting service is in the control of large 
groups of lamps in such installations as public buildings, 
theatres (Div. 9), train sheds, isolated sections of plants or 
docks, factory buildings, and the like. Although switches 
of this type are frequently employed to provide control of 
a motor from a distant point, the material pertaining to 
remote-controlled switches which is contained in this division, 
applies principally to lighting-circuit control. 

318. Remote-controlled Switches May Be Classified Accord¬ 
ing To Operation as: (1) Held closed mechanically (Fig. 387); in 
the switches of this class, the switch is closed by one electro¬ 
magnet and is held closed by a latch mechanism. Usually 
there is a second electromagnet which, when energized, releases 
the latch, whereupon the switch is opened by gravity, by a 
spring, or by the electromagnet. (2) Held closed electrically 
(Fig. 402); that is, in the switches of this class, the energiza¬ 
tion of the electromagnet closes the switch, and so long as 
current flows through this electromagnet, the switch (Fig. 385) 
is held, by the magnetic pull, in the closed position. Then if 
the current through the electromagnet is discontinued, the 
switch is opened by gravity or by a spring. This electro¬ 
magnet may (Sec. 327) have two windings. Switches of each 
classification are described in the following sections. 

Note.—An Electrically-held-closed Remote-controlled Switch 
Is Better Adapted For The Control Of Motors Than For The 


272 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


Control Of Lamps. This is because such a switch (Sec. 327) inherently 
provides low-voltage protection to the load circuit. Thus, in the event 
of a failure in the power-supply, the current through the electromagnet 
will be discontinued; the switch will open; and the motor will be dis¬ 
connected from the line. 

Note.—A Mechanically-held-closed Remote-controlled Switch 
Is Better Adapted For Use In The Control Of Lamps Than Is 
One Which Is Held Closed Electrically. This is because: (1) Low- 
voltage protection is usually neither required nor desired for lamps. (2) No 
current is wasted in holding the switch closed. 


Movable 
j|'< Contactor. 


.■Stationary Contactor- 

* 

5 I A .-Movable Contactor 
oiS Uj', Slate Base-. 

aU-S haped 
"k ? Con tact bar 

■> 

& 

>'Control 
Circuit, 

. Leaoly 

[§£U Spring : 
n 'Closing Coil-' 

If Connec ting L ug■ ■ 

I- 5 traight-Line 
Movement Type 

Fig. 386.—Illustrating two types of 
remote-controlled-switch construction. 
(Both switches are in the open position.) 




319. The Two Principal Types Of Remote-controlled 
Switches are: (1) The straight-line-movement type (Fig. 386-1) 

wherein two movable con¬ 
tactors, C, which are carried 
by a U-shaped contact bar, B, 
in opening and closing, move 
inward and outward in a straight 
line. (2) The clapper type (Fig. 
386 -II) wherein the movable 
contactor, C, is carried by a 
contact finger, B, which in 
opening and closing, oscillates 
about the pivot, P. Electric- 
ally-held-closed switches (Sec. 
318) and mechanically-held- 
closed switches (Sec. 318) of each of these types are described 
in following sections. 

320. A Three-pole, Straight-line-movement, Mechani¬ 
cally-held-closed Remote-controlled Switch is shown in 
Fig. 387. Except during the almost-instantaneous period of 
opening and closing, no current is required for the operation of 
this switch. This feature is provided by a device which, after 
the switch is closed, automatically opens the closing-coil 
circuit and closes the opening-coil circuit. Then, when the 
switch is opened, the opening-coil circuit is opened, and the 
closing-coil circuit, is closed. Therefore, when the switch is 
open, current can only flow through the closing-coil circuit. 
Or, when the switch is closed, current can only flow through 
the opening-coil circuit. Consequently, even if either of the 
momentary-contact switches (Fig. 388) be held closely inde- 


























Sec. 320] 


REMOTE-CONTROLLED CIRCUITS 


273 


: :o: 





a 


B 

Tf 


•.••.o' 



<£■ - - State Base 

Laminated Contact 
Brushes . -^y ) 4 

A 



Switch-Frame- 


1- Front View 

*0 /Plate 


Copper Block- -%d;.,• 
Connecting Lug- - 


l C: A 






Closing} 
Coif 


Closing- 
Xolt' 



H-5ide Yiew (Switch Open) 

.'U-Shaped Yoke 

X 

o 

Closing- 



Opening^ -;--- 

^Cofl H- Bottom View Of Switch- 
Frame Showing YYiring 


Fig. 387.—Three-pole remote-controlled switch of the straight-line movement type 
which is held closed mechanically. {Type F, Hart Mfg. Co.) 



I-Switch Open: Closing-Coil Circuit,Closed: Opening-Coil Circuit,Open 



(T 




-u 


t5^ 

•V <- 


1 


■ + 
■± 


*•In Opening-Coil Circuit 


r n 


^. 

H-Switch Closed: Closing-Coil Circuit,Open: Opening-Coil Circuit, Closed 

Fig. 388.—Wiring diagram of the opening and closing coils of a Hart Type F switch. 

{Hart Mfg. Co.) 


18 























































































































































































274 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


finitely, no current will flow through the control circuit 
except during the very short period while the switch is opening 
or closing. The method of operation is explained below. 


Explanation. —The switch (Fig. 387) is held in the open position by a 
spiral mainspring (not shown). When the switch is closed and locked 
this spiral mainspring is compressed. Then when the locking mechanism 
is released, the compressed mainspring kicks the switch open. The 
method of closing the switch and of releasing the locking mechanism is 
explained in the following paragraphs. 



Knurled Knob 


r* "Plate- 


Opening 
Coil\ VT/ 


Container 


-Spring f 


\5pringN\ 


'Insulation 


'Contact: 


Fig. 389.—Illustrating locking mechanism and the method of connecting and dis¬ 
connecting the opening and closing-coil circuit of Hart Type F remote-controlled 
switch. 


The laminated contact brushes ( B , Fig. 387) are carried by U-shaped 
yokes, U. These U-shaped yokes extend across the switch frame, F, 
and downward on either side of F, so that B may contact with the copper 
blocks, A, to which are bolted the connecting lugs, L. The brush yokes, 
U, are in turn carried by a plate, P (Figs. 387 and 389), to which are 
attached the cores, K (Fig. 387-7 1 /), of the closing coils. The switch 
is provided with two closing coils (C, Fig. 387-7/7) which are (Fig. 388) 
connected in series. Hence, when the closing coils, C, are energized, the 















































































































































































8ec. 320] 


REMOTE-CONTROLLED CIRCUITS 


275 


cores, 7v, are pulled downward, thus closing the switch. The current 
path through the closing coils is indicated by the arrows in Fig. 388-7. 

When the switch closes, it is automatically locked closed as follows: 
Three steel balls (H, Fig. 389, only two of which are shown) are held in a 
container, I). The spring, .7, is under compression and consequently 
pushes downward on the tapered-pin, M, which bears against the steel 
balls. The container, I), and the pin, M, are carried by the plate, P. 
As the switch is closed, P, M and D move downward until the balls slip 
outward under the edge of a fixed recess as shown in Fig. 389-77. When 
the balls slip into this recess, sufficient space is provided between them 
so that M, actuated by the spring, J, continues its downward movement 
to the position shown in Fig. 389-77. When M is in this position, the 
balls are held, partly under the edge of the recess and partty in the con¬ 
tainer D. Therefore, D cannot move upward. And since D is carried 
by the plate, P, the switch is locked closed. 

As the movement of the pin M is continued downward by the spring, 
J , the lower end of M strikes the top of the opening coil core, N, and 
forces it downward. As N is forced downward, the contact bar, E, which 
is in circuit with the closing-coils (Fig. 388-7), is moved away from 
the contacts (Figs. 388-77 and 389-77). Thus, the closing-coil circuit 
is opened. Also, as N is forced downward, the contact bar, G (Figs. 
388-77 and 389-77) closes the opening-coil circuit. Furthermore, this 
downward movement of N compresses spring T. Therefore, when the 
switch is closed, the closing-coil circuit is opened, and the opening-coil 
circuit is closed. 

If the pin ( M , Fig. 389-77) is now pushed upward, the balls, H, will 
slip out of the recess and the mainspring will snap the switch open. 
The pin, M, may be pushed upward manually by pulling on the knurled 
knob, Q. The pin, M, may also be pushed upward and the switch 
opened as follows: By closing the momentary-contact switch (P, Fig. 
388-77), current will flow, as indicated by the arrows, through the 
opening coil (O, Fig. 389-77). The magnetic force thus exerted by O 
raises the opening-coil core, N (Fig. 389-77), and pushes M upward. 
The balls, 77, are thereby disengaged from the recess and the switch 
opens. When N begins its upward movement, spring V acts to hold the 
contact bar, G, downward, so that the opening-coil circuit is kept closed 
until the switch is unlocked. When the switch is unlocked it opens, and 
spring T raises bars E and G to the position shown in Fig. 389-7. Thus 
the opening-coil circuit is opened and the closing-coil circuit is closed so 
that all is in readiness for the next operation ot the switch. 


276 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


321. Table Showing Currents Required To Operate Type F 
Remote-controlled Switches. (Hart Mfg. Co.) 


►Size of switch 

Control circuits 

Closing coils, 
amp. 

Opening 
coil, amp. 


15 V., D.C. 

6.5 

13.0 


30 V., D.C. 

5.2 

7.5 


50 V., D.C. 

3.2 

4.5 

30, 60, and 75 amp. 

125 V., D.C. 

2.2 

4.6 

2-, 3-, or 4-pole 

250 V., D.C. 

1.7 

1.2 


1 125 V., A.C. 

2.2 

0.5 


*250 V., A.C. 

1.1 

0.25 


x 440 V., A.C. 

0.55 

0.13 


125 V., D.C. 

2.3 

5.0 

100, 150, and 200 

250 V., D.C. 

1.25 

2.0 

amp., 2-, 3-, or 4- 

1 125 V., A.C. 

9.0 

1.5 

pole 

1 250 V., A.C. 

3.5 

3.7 


*440 V., A.C. 

1.8 

1.2 


1 60 cycles. 


Note.—These Switches Will Operate Satisfactorily At Approxi¬ 
mately 15 Per Cent. Above And Below Their Respective Voltage 
Ratings. That is, a switch which is rated at 110 volts will operate 
satisfactorily at 95 or 125 volts. 

322. A Mechanically-held-closed Remote-controlled Switch 
Of The Clapper Type is shown in Figs. 390 and 391. Switches 
of this type are regularly manufactured (Fig. 392) with 
one, two, and three poles. Pressing the “close” button 
of the momentary-contact switch (M, Fig. 393) energizes the 
closing coil (A, Fig. 390). The magnetic pull thus exerted 
closes the switch and it is automatically locked. Then, 
by pressing the “open” button (M, Fig. 393), the opening coil, 
( B , Fig. 390) is energized. This releases the lock and the 
switch is opened by gravity. As long as either one of the 
momentary-contact switches (M, Fig. 393) is held closed, 
current will continue to flow through the coil which is con¬ 
trolled (Sec. 329) by that switch. However, current-flow 
through the coil will cease as soon as the momentary-contact 






















Sec. 322 ] 


REMOTE-CONTROLLED CIRCUITS 


277 



I-5ide View Show¬ 
ing How Switch May 
Be Manually 
Opened 


U> Fron t View 

A< 


Ht-Sec+ion A-A 


Shows How Switch May 
Be Electrically 
Opened 

Fig. 390. —Three-pole, mechanically-held-closed, remote-controlled switch of the 

clapper type. {Cutler-Hammer Mfg. Co.) 



HSwitch Closed But Not Locked 


Fig. 391. —Illustrating method of closing and locking of a mechanically-held-closed 
remote-controlled switch, simplified for purposes of illustration. ( Cutler-Hammer 
Mfg. Co.) 














































































































































































































278 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


switch is permitted to open. The operation is explained in 
detail below. 

Explanation. —Corresponding parts in Figs. 390 and 391 are desig¬ 
nated by the same reference letters. The switch is shown in the open 
position in Fig. 391-7. The contact finger, F, is secured to the switch 



Fig. 392. —Drilling dimensions of single-, double-, and three-pole remote-controlled 
switches. (Clearance dimensions as shown in side view are the same for each switch 
shown in II, III and IV. Cutler-Hammer Mfg. Co.) 


frame, N, by a bolt and the spiral spring, S. The switch frame rotates 
from the open to the closed position, and vice versa, about the pivot, P. 
When the closing-coil, A, is energized, the magnetic force moves the 
switch frame, N, and the contact finger, F, to the position shown in 
Fig. 391-/7. At this point of the switch-frame travel, F is stopped by 
striking the contact-block, B. However, the magnetic force of A is still 
acting on the frame N. This force compresses the spring, S, and moves 


1 jLinesILi 



31 

y 

• , v ff 

1 

f_H 


r 


1- 

[1 

St 

. ) . * . 

t 

|Load| 


Confacf 
/Fingers 'x 

y_jA- Open-. 



|L i ne s| Momentary- 
Contact 
Snitch \ 



M 

„ Close- , 

''Closing Coils*’' I Lo a d 

l-S ingle-Pole R- Double-Pole El- Th r c e - Po \ e 

Fig. 393.—Remote-controlled-switch wiring diagrams. ( Cutler-Hammer Mfg. 


Co.) 


N onward to the left, so that the notch in the latch, E , engages the roller, 
R (Fig. 390-7), which is carried by the frame, N. The switch is now 
closed and locked closed. The same operation may be manually per¬ 
formed by pushing to the left (Fig. 391) on the closing handle, K. 

Energizing the opening coil, B (Fig. 390-777) exerts a downward pull 
on the latch, E. This disengages E from the roller. The spring S now 
expands and moves the frame back to the position shown in Fig. 391-77, 
whereupon the switch is opened by gravity. The switch is manually 














































































































































Sec. 323] 


REMOTE-CONTROLLED CIRCUITS 


279 


opened as follows: Pushing to the left (Fig. 390-7) on the opening handle, 
G, causes the latch, E, to move downward. Thereafter, the switch is 
opened in the same manner as that explained above for the electrical 
operation. 



Back 

Connecting 

Stuoi 


Fuse Clips — 




Con fact 


Finger F 


Roller 


Spring S 

Frame 

y' D 

Closing Coif Armotfure 


Opening Coti B v 
Opening-Coil Armature SC 


Contact 
Block E 


Latch „ L 


Slate Base 


Closing Coll 
—Pigtail 


Fig. 394.—Two-pole, mechanically held-closed remote-controlled switch of the clapper 

type. ( Frank Adam Electric Co.) 


323. The Major Remote-controlled Switch (Figs. 394, 395, 
and 396) is a mechanically-held-closed switch of the clapper 
type. The general construction and operation of this switch 





280 LIGHTING CIRCUITS AND SWITCHES [Diy. 8 

is similar to that of the switch of Figs. 390, 391 and 393; the 
differences are enumerated below. Current will flow through 
the opening and closing coils (B and ^4) as long as the con¬ 
trolling momentary-contact switch (M, Fig. 396) is held closed. 
Since the coils in this particular switch are designed for 
continuous duty, no damage to them will be caused, even if the 


Opening Coil 

yV, . Opening-Coil 
Armature 


r, , -Contact 
y blocks 


.-■■Closing 
Coil 



,-F 

'-Contact 

.Finger 


L I Latch 

/ 

''Spiral Spring 

% Flexible 
'Connector 


I- 5 1 d e V t e w 



H- F ro n + View 


Fig. 395.—The Major remote-controlled switch. (Frank Adam Electric Co.) 


current-flow is permitted to continue indefinitely. This 
switch is of very rugged construction. It is therefore well 
suited for theatre service (Div. 9) where frequent operation is 
required. The method of operation is explained below. 

Explanation. —Those reference letters which appear in each of Figs. 
394, 395 and 396 are used to designate corresponding parts. This 
switch is similar in construction to that described in Sec. 322. Each 
contact finger, F, is secured to the switch frame by a bolt and a spiral 
spring ( S , Figs. 394 and 395). When the switch is being closed, the 
contact fingers, F, strike the contact blocks, E, before the latch, L, 
engages the roller, R. Then, the continued magnetic force of the closing 








































































































































Sec. 324] 


REMOTE-CONTROLLED CIRCUITS 


281 


coil. A y on the closing-coil armature, D, compresses spring S, and pulls 
the frame onward. As soon as R, which is carried by the switch frame, 
moves to the position corresponding to that shown in Fig. 396-/, the 
latch, L, is pulled downward by gravity and engages the roller, R. 
Thus, the switch is closed and locked closed. 

Now, by closing the opening-switch of the two-circuit momentary- 
contact switch (M, Fig. 396) the opening coil, B is energized. The 
, magnetic force which is thereby exerted on the opening-coil armature, C, 
raises the latch, L , from the roller, R. The switch frame being thus 
released, spring S expands. Then, the momentum, which is given 
to the switch frame by the sudden expansion of S, together with gravity 
causes the switch to open. The switch may be manually closed by 
pushing inward on the closing-coil armature ( D , Fig. 394). The switch 
may be manually opened by raising latch L with the finger. No handles 
are provided. 


.■Contact Block A. 

Opening Coil _. -Opening-Coil Armature ,C 
,--Latch\_ p'' 



-Two-Circuit Momentary- 
Contact Switch 
<--Line -->». 


Closing Switch 

"-Closing-Coil 
Armature , D 



I-Switch Closed 


Loac/--■> 

H-SwHch Open 



Fig. 396.—Illustrating the operation of the Major remote-controlled switch. (Frank 

Adam Electric Co.) 


Note.—The Voltage And Current Ratings Of The Major 
Switch are these: This switch, as regularly manufactured, is designed to 
control a load-circuit current of 100 amp. at 250 volts. The slate base is 
ordinarily drilled so that either 100-, 60-, or 30-amp. fuse clips may be 
secured thereto. When the switch is electrically operated, the maximum 
values of the current which flow through the opening and closing coils 
are: (1) Alternating current; 7.7 amp. for closing, and 2.1 amp. for 
opening. (2) Direct current; 2 amp. for closing, and 0.5 amp. for opening. 
Since the time during which this operating current flows is so short that 
it may be considered almost instantaneous, only a very small amount of 
energy is required to electrically open and close the switch from a remote 
location. 

324. A Two-pole, Mechanically-held-closed Remote-con¬ 
trolled Switch Of The Clapper Type is shown in Fig. 397. 
The plane of movement of the contact fingers, F, is parallel to 
the switch base. There is only one coil, C, which serves both 
to open and close the switch. No current flows through this 


















































282 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


coil except during operation. The method of operation, is 
explained below. 

Explanation. —The two contact fingers (F Fig. 397) are connected 
by an insulated plate, M. This plate is connected to the lower end of 



Fig. 397.—Two-pole mechanically-held-closed remote-controlled switch of the clapper 

type. (Automatic Switch Co.) 

the weight, W, which oscillates about the pivot, P. The magnet core, 
A, is connected through a link to the upper end of W so that when A 
is jerked upward by the electromagnet, C, it passes over the center and 
drops by gravity to the dotted position, thus closing the switch. The 
lower end of W is provided with a movable contactor, N. When the 
switch is in the open position (Fig. 397), N contacts with the stationary 



























































































Sec. 325] 


REMO TE-CON TROLLED CIRCUITS 


283 


contactor S. Now by pressing the “on” button of the momentary- 
contact switch, the circuit through the electromagnet is completed, the 
core is jerked upward and the switch is closed as explained above. The 
circuit thus formed by pressing the button may be traced as 
follows: From L\ through C to the pivot of IF, through IF and the movable 
contactor, N, to the stationary contactor, S, and from S through the 
momentary contact switch to the neutral, L 2 . When the switch is closed 
the movable contactor, N, as shown by the dotted position, now contacts 
with stationary contactor T. Then by pressing the “off” button of the 
momentary-contact switch, C will be energized and the switch will be 
operated back to the open position. The circuit formed by pressing 
the “off” button may be readily traced by referring to Fig. 397. 

325. Another Mechanically-held-closed Remote-controlled 
Switch Of The Clapper Type is illustrated in Fig. 398. When 


r Opening-Coil Terminal 

Walking \ Control-Circuit Closing-Coil 

beam \ Wires .Closing-Coil Contactor 

/ Terminals 
Jr- 




Closing-Co/i 
Core Opening-Coil 
•' . Core-~ x 

.Walking 
• beam 


Arm 


i<- 0 ApproXi 

X-Front View 


'Laminated >. 

•° Contact brush pL 


XL-Si ole View 



Fig. 398.—Three-pole, mechanically-held-closed, remote-controlled switch. ( Sunclh 

Electric Co., Bui. 7200.) 


the switch is closed (Fig. 398 -II), the laminated blushes, B, 
bridge the upper and lower contact blocks, thus completing 
the circuit through the switch. When the switch is opened 
the brushes fall outward. The method of operation is 
explained below. 

Explanation. —In Fig. 398, the laminated brushes, B are secured to 
the arm, A, which is pivoted to the switch frame, F, at P. In opening 
and closing the switch, the arm, A, oscillates about the pivot, P. The 
poller ( R , Fig. 398-7//) is carried by the lower end of the closing-coil 























































































































284 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


+ 

a- 

<- 


Generator Mains -. 


<-• 


. uo-v.- 

-770-V. - 


> c- 




H 


A' 


> 


UO-Vr - 


> 


■Momentary- 
Contact Push 
Button Control 
Switches 


Common Or 
Neutral Wire 


> 


.Contactor 


core, C. When C is raised by the closing coil or lowered by gravity, 
R rolls up or down along the inner side of the switch frame, F. (The 
contact brushes and a portion of the arm are omitted in III). The 
same pivot which carries R also carries one end of the link, L. The other 
end of L is connected to the arm (A, Fig. 398 -III) at D. Thus, by raising 

and lowering the closing-coil core, C, 
the arm is caused to oscillate about 
P, thereby closing and opening the 
switch. When the roller, R is pulled 
upward beyond the lower center-line 
(Fig. 398-///), the spring action of 
the brushes, B, acting through the 
arm, A, and the link, L , tends to push 
the core upward still further. But the 
core is now at the upper end of its 
travel and can move no further up¬ 
ward. Therefore, the switch is, by 
virtue of R and L being “off center,” 
locked closed. When the core is 
pushed downward, so that the center 
of R passes below the lower center- 
line, R is free to roll down the side of 
F, and the switch opens. 

In Fig. 398 -II, the switch is in the 
closed position. By closing the 
momentary-contact switch (Fig. 399) 
which controls the opening-coil cir¬ 
cuit, the opening coil is energized, 
and the opening-coil core (0, Fig. 
398 -III) is raised. When O is raised, 
it strikes the pin, E , thus raising the 
right-hand end of the walking beam, 
IF, and forcing down the left-hand 
end of IF. When the left-hand end 
of IF is lowered, it strikes pin, F, 
thereby pushing the core, C, down¬ 
ward. This moves R downward, 
and unlocks it and the switch is 
opened, as explained above. As will 
be apparent from a study of Fig. 399 
when the remote-controlled switch 
is open, the opening coil cannot be 
energized. Also, as the right-hand end of the walking beam, IF, is 
tilted upward, the roller, G, permits the spring, S, to push the lower end 
of the closing-coil contactor, H, to the left. Thus, the upper end of H is 
caused to move to the right and contact with two small pilot contacts on 
T, thereby closing the closing-coil circuit. 



Opening 

Coil-' 


w-dosing 
Coil 


o 



L 


L 

o 


o 




Load ■ 


Fig. 399.—Wiring diagram of me¬ 
chanically held-closed remote controlled 
switch, (The mains are connected to 
terminals marked M; the oening 
coil to terminal L ; the closing coil is 
connected to terminal M. Sundh 
Electric Co., Bui. 7200.) 














































Sec. 326] 


REMOTE-CONTROLLED CIRCUITS 


285 


When the closing coil is energized by closing its momentary-contact 
switch (Fig. 399), the core C is raised. The switch is closed and locked 
closed as explained above. Also, when C is raised, the left-hand end of 
the walking beam, IF, is, by the pin F, tilted upward. Consequently, 
the right-hand end of IF tilts downward. Thus, as will be apparent 
from the illustration (Fig. 398-/ 11), the roller, G which is carried by W, 



Fig. 400.—Two-pole, electrically-held-closed remote-controlled switch of the clapper 

type. (Sundh Electric Co.) 


causes the upper end of H to move to the left. The closing-coil circuit 
is thereby opened as soon as the switch is closed. 


326. An Electrically-held-closed Clapper Type Of Remote- 
controlled Switch is illustrated in Fig. 400. Switches of this 
type are sometimes called magnetic switches, or magnetic 



<- -Load- >| 

I-Closed 


Magnet 


Single-Pole 
Switch 


Control- 
Circuit / 
Wires-'-\ 


- -Remote-Controlled 
Switch 




Fig. 401.—Control-circuit diagram for electrically-held-closed remote controlled 

switch. 


contactors. As indicated in Fig. 401, current must, to hold the 
switch closed, flow through the magnet, M. Closing switch 
S (Fig. 401 -II) energizes M. The armature A is thereby 
attracted, and the contact fingers, F, are pulled to the closed 






















































































































28(3 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


position (Fig. 401-7). If S is opened, or if the service is 
interrupted, M will become de-energized and the switch will 
be opened by gravity. If the switch is opened by an inter¬ 
ruption in the voltage supply, it will be reclosed upon resump¬ 
tion of service. 

327. A Two-pole, Electrically-held-closed, Straight-line - 
movement Remote-controlled Switch is shown in Fig. 402. 

Although this switch is specially adapted for the control of 
motors, it may be used to control lighting circuits. Remote- 



Fig. 402.—Two-pole, electrically-held-closed remote-controlled swatch. The switch 
is shown in the open position. (Type A, Hart Mfg. Co.) 

controlled switches of this type are so made that they may be 
controlled (Sec. 322) either by momentary-contact switches, 
single-pole switches or three- and four-way switches. When 
this switch (Fig. 402) closes, it is mechanically locked closed. 
However, as explained below, a small current is required to 
prevent it from unlocking and opening. 

Explanation. —By closing the single-pole switch ( S , Fig. 403-7), the 
closing coil, A, is energized. This raises the remote-controlled switch, 
R, to the closed position shown in II. As R is being closed, the following 
operations occur almost simultaneously: (1) The switch is locked in the 




















































































































































































































Sec. 328] 


REMOTE-CONTROLLED CIRCUITS 


287 


closed position. (2) The holding coil , B, is energized. (3) The core of 
B is lifted , thereby disconnecting the closing coil , A, from the circuit. As 
long as the proper voltage is maintained between C and D (Fig. 403 -II), 
the current through B will hold the core of B upward in the position 
shown. If the current-flow between C and D is interrupted, either by a 



Fig. 403. —Illustrating operation of a Hart Mfg. Co. Type A remote-controlled switch. 
(The fuses shown herein are for protection of the coils.) 


failure in the power supply, or by opening S, B will be de-energized, and 
its core will drop. The switch mechanism is so designed that when the 
core of B drops, the locking device is tripped, thus permitting R to open. 
If R is opened due to a power-supply failure, it will, provided S remains 
closed, reclose upon resumption of service (see also Sec. 322). 


328. The Control Circuits Of A Remote-controlled Switch 

are those circuits which carry the current for opening and 


Line 



Opening-Coil-Circuit Wires.,,., tolling SoiMm. 


M 


Opening Co/7 


B 




■'.-Closing Coil 


Closing-Coil-Circuit Wires' ■ 


Remote-Controlled Switch 


Fig. 404. —Illustrating the control circuit of a remote-controlled switch. 


closing it. The control circuits consist of: (1) The opening 
and closing coils, 0 and C, Fig. 404, which are mounted on the 
remote-controlled switch. (2) One or more controlling switches, 
D and E, Fig. 404, which are installed at the control locations. 
(3) The wires, A and B, (Fig. 404) which connect the opening and 


















































































288 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


closing coils to the controlling switch. The control-circuit 
connections and the type of the controlling switches which are 
used in the control circuit will usually depend upon the type 
of the remote-controlled switch. In general, the mechanically- 
held-closed switches are controlled (Sec. 329) by momentary- 
contact switches, and the electrically-held-closed switches 
are controlled (Sec. 322) by single-pole, or three- and four-way 
switches. Control-circuit diagrams for remote-controlled 
switches of various types are described in the following 
sections. 


Note.—The Size Of The Control-circuit Wires For A Remote- 
controlled Switch can not be smaller than No. 14, B. & S. gage to 
insure compliance with the Code. Ordinarily No. 14 is sufficiently 
large to carry the current. See Table 321 for control currents required 
to operate Hart remote-controlled switches, which are in general typical 
of the currents required to operate the remote-controlled switches of 
other makes. See Sec. 323 for currents required to operate the major 
remote-controlled switch. If the control-circuit is excessively long, the 
size of the wire used for it must be sufficiently large that the voltage 
drop in it will not exceed about 15 per cent. 


329. Remote-controlled Switches Of The Mechanically- 
held-closed Type Are Generally Controlled By Momentary- 

contact Switches. Two momentary- 
contact switches (.D and E, Fig. 404) 
are usually required: One for the open¬ 
ing-coil circuit and one for the closing- 
coil circuit. Therefore, for economy of 
installation, two momentary-contact 
switches which are contained in the 
same porcelain casing (Figs. 79 and 405) 
and which have a common binding-post 
(P, Fig. 404) are ordinarily employed for 
the control of this type of remote-con¬ 
trolled switch. 


Porcelain 

Casing 



\ 

§ 

@ I 

f- 

6 

a 

.'/• -Cv 

i 

1 

& 

\ 

8 

k S 





Fig. 405.—Two-circuit 
push-button, momentary- 
contact snap switch. ( Cut¬ 
ler-Hammer Mfg. Co.) 


Note.—Circuit Diagrams For Single¬ 
location Control Of Remote-controlled 
Switches By Means Of Momentary-Contact 
Switches are shown in Figs. 388,393,396 and 397. 


330. Multi-location Control May, For Those Remote- 
controlled Switches Which Can Be Operated By A Momen- 














Sec. 331] 


REMOTE-CONTROLLED CIRCUITS 


289 


tary-contact Switch, Be Obtained as shown in Figs. 406 and 
407. As indicated in Figs. 388, 393, 396, and 397, the con¬ 
nections for the momentary-contact switch will be somewhat 


—pi 

^_ 

'To Control-Wire 
Binding-Posts 
On Remote- 
Controlled Switch 



\r \ , 

'• • Two-Circuit Momentary-Contact Switches 


Fig. 406.—Showing connections of two-circuit momentary-contact switches for multi¬ 
location control of remote-controlled switches. 




5 


■"wvwmwww 




a 




3— Floor 


71 


j-\Two-Circuit, Momentary 
' Contact Switches 




7- Floor 


11 * 


different for the various remote-controlled switches. There¬ 
fore, when it is desired to provide more than one control 
location for a momentary-contact-controlled remote-con¬ 
trolled switch, first determine 
the correct connections for 
single-location control (Sec. 

329). Then install a two-circuit 
momentary-contact switch at 
each desired control location. 

Connect the common binding- 
post (P, Fig. 406) of each 
momentary-contact switch to 
the same wire, B, Fig. 406. 

Connect one of the remaining 
binding-posts of each switch to a 
second wire, as A, and connect 
the other binding-post of each 
switch to the third wire, C. 

331. A Considerable Wire 
Saving May Frequently Be 
Effected In A Remote-control 
Installation By Using A Com- 
mon Wire For All Momentary- F,<J - 407 ,- Fot re “°‘° c ° nt r. ol , of a 

. vacuum cleaner motor controlled on 
contact Switches as shown in each floor by momentary-contact 

Fig. 408. The common control switches connected in parallel. (Ho.,1 
& Mfg. Co., Catalog F.) 

wire (IT, Fig. 408) is connected 

to one side of the main and to the center contact (P, Fig. 406) 
of all of the two-circuit momentary contact switches. The 

19 


■ 




1- Floor 


outs-^d.^ 


—aisjr> 




-- 

casu> —• i» -i 


Line-''--'- 71 
Remote-Controlled Switch- 







































































































290 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


other two terminals of each momentary-contact switch are 
connected, one to one end of the opening coil, 0, and one to 
one end of the closing coil, C. The other ends of each 0 and C 
are connected to the other side of the main. The control cir¬ 
cuit of each remote-controlled switch may be readily traced 



v-.-Seven No. 14 Control Wires 


Remote-Controlled Switches / 
Mounted In Same Pane! 3ox-'' 


w 

Common 
Wire i For AH 
Switches- 

Closing Coil 


Two-Circuit Momentary-Contact / 
Switches Mounted In Gang.--'' 



Fig. 40S.—Showing how a wire-saving may be effected by using a common wire for 
all momentary-contact swatches. (See Sec. 337 as to fusing of control-circuit wires.) 


by referring to Fig. 408. This method of connections may 
(see note below for limitations) be used with practically any 
mechanically-held-closed remote-controlled switch. It is 
especially suitable for those installations wherein a number 
of remote-controlled switches (Fig. 409) are mounted on the 



Fig. 409.—Remote-control system for the lights on one floor of a hospital. 


same panel board, and where the controlling switches therefor 
are mounted in gang at one control location. The wire-saving 
which will then be effected by this method over the ordinary method 
shown in Fig. 406 = (the number of remote-controlled switches 
— 1) X (the average distance between the momentary-contact 
switches and the remote-controlled switches). 



































































































































































Sec. 331] 


ft EMC) T E-CON TROLLED CIRC UITS 


291 


Note.—A Common Momentary-contact-switch Wire May Not 
Be Desirable For All Remote Controlled Switch Installations. 
Where the momentary-contact switches are not grouped at a single 
location but instead are distributed at a number of different locations 
throughout the building, a common wire should not, usually, be employed. 
The reason for this is that trouble—a ground for example—at any point 
on the long common wire might throw trouble on all of the momentary- 
contact-switch circuits. If this occurred, the trouble would probably be 
difficult to locate and correct, because of the great length and the ramifi¬ 
cations of the common wire. Hence, where the momentary-contact 
switches are not grouped, the wiring arrangement shown in Fig. 410 
is usually preferable. Before installing a system wired as in Fig. 408, 
it would be advisable to obtain the approval of the local wiring 


Center last wing Wes+Wing 

1 ~Qh 

-Q- -Q- 


1st Ward 


2nd Ward 

i 1 



Center- - 

East Wing- - - 


/West Wing 
. f v,.- -1st Ward 

-<—2nd Ward 


Mains 



<- - - -Controlling Wires Running To Remote-Controlled 

Switches 

\S- -Momentary-Contact Switches Located tn Main Office 

Fig. 410. —Wiring-diagram of a remote control system wherein five remote-controlled 
switches arc employed. (Hart Mfy. Co., Catalog F.) 


inspector; while there appears to be no Code rule which this wiring 
would violate, there might be some local requirement with which it would 
conflict. 

Example. —A Remote-control System For The Lights On One 
Floor Of A Hospital is shown in Fig. 409. The lights in each of the 
various wings and in each of the wards are controlled by the momentary- 
contact switches located in the main office. The wiring diagram as 
indicated in Fig. 410, requires, for each remote-controlled switch, three 
control wires extending from the momentary-contact switches to the 
remote-controlled switches. By arranging the connections as indicated 
in Fig. 408, four of these control wires may be eliminated. Assume that 
it is 50 ft. from the momentary contact-switches to the remote-controlled 
switches. Then according to the rule stated above, since there are five 
remote-controlled switches, the wire-saving which will he effected = (5 - 1) 
X 50 = 200 ft. of No. 14 wire. 

































































































292 LIGHTING CIRCUITS AND SWITCHES [Div. 8 

332. Multi-location Control For Those Remote-con¬ 
trolled Switches Which Are Operated By Single-pole Switches 

(Figs. 401 and 403) may be obtained by substituting the 



Fig. 411.—Multi-location control of an electrically-held-closed remote-controlled swatch 
using three-and four^ay snap swatches. (Hart Mfg. Co., Type A.) 

required number of three- and four-way switches (Fig. 411) 
for the single-pole switch of Fig. 403. 



Fig. 412.—Special momentary-contact swatch used to operate an electrically-held- 
closed remote-controlled swatch. (Hart Mfg. Co., Type A.) 

Note.—The Electrically-held-closed Switch Shown In Fig. 
403 May Be Controlled By A Momentary-contact Switch by mak¬ 
ing the connections as shown in Fig. 412. A special two-circuit 
momentary-contact switch (Hart Mfg. Co., List No. 093) is required. 
This switch has one side, O (Fig. 412) normally closed, and one side, 




























































































Sec. 3331 


REMOTE-CONTROLLED CIRCUITS 


293 


C, normally open. With the remote-controlled switch, R, in the open 
position, closing switch C closes R. When R closes, it locks and dis¬ 
connects the closing coil as explained in Sec. 327. The control circuit 
through the holding coil is then made through the momentary-contact 
switch, 0. If O is opened the holding coil is de-energized and switch 
R opens. If R opens because of a power-supply failure, it will not reclose 
upon resumption of service until switch C is operated. 

333. Two Or More Remote-controlled Switches May Be 
Operated By One Two-circuit Momentary-contact Switch 

by arranging the control-circuit connections as indicated in 
Fig. 413. If the switches A and 
B are closed, operation of switch 
N will simultaneously open A and 
B. If A and B are open, opera¬ 
tion of M will simultaneously 
close both A and B. Additional 
remote-controlled switches may, 
by connecting their opening and 
closing coils to wires D, E and F 
in the manner indicated in Fig. 

413, be controlled by MN. The 
maximum number of switches 
which may be so controlled will 
be governed by the safe current-carrying capacity or by the sale 
current-breaking capacity of MN. That is, the product of 
the number of remote-controlled switches by the current- 
value in amperes which is required to close one switch should 
not exceed the safe current-carrying or the safe current-break¬ 
ing capacity of MN (see examples below). 

Example.— Assume that a current of 5 amp. is required to close 
one remote-controlled switch, and that the closing-cui rent of each switch 
is interrupted (Secs. 320 and 325) by the remote-controlled switch 
mechanism. Then if five remote-controlled switches are to be operated 
by one momentary-contact switch (MN, Fig. 413) the rated current- 
carrying capacity of MN should be at least'. 5 X 5 — 2o amp. 

Example.— Assume that the remote-controlled switches are of a type 
(Secs. 322 and 323) wherein the operating current is broken by the 
momentary-contact switch. Then the maximum number of remote- 
controlled switches which should be controlled by one momentary-contact 
switch will be governed by the maximum current which can be safely 



Fig. 413.—Circuit diagram for con¬ 
trolling two remote-controlled switches 
with one two-circuit momentary-con- 
tact switch. 



































294 


LIGHTING CIRCUITS AND SWITCHES 


fDrv. 8 


broken by the momentary-contact switch without causing excessive 
damage to its contacts. That is, assume that a controlling switch has a 
continuous-duty rating of, say, 60 amp.; but with frequent operation, 
45 amp. is the maximum current which this switch will interrupt without 
causing serious damage to its contacts. Then, if the minimum current 
‘ required to close each remote-controlled switch is 7 amp., not more than 
(45 -r 7 = 6.4) six remote-controlled switches should be connected to 
one of these momentary-contact switches. 


334. Manual Double-throw-Switch Operation Of Two 
Mechanically-held-closed, Remote-controlled Switches May 
Be Provided as shown in Fig. 414. Remote restricted control 
(Sec. 15) of lamp-groups C and D is thereby provided, as 
explained below, by the two-circuit momentary-contact 
switch, MN. 




..--Lamps-- 
- -Branches---■> 
■•--Opening 

- r m'L . - * 





• Two-Circuit Momentary-Contact Switch j 

-Remote-Controlled Switch- 


ig. 414.—Circuit diagram for two mechanically-held-closed, remote-controlled 
switches connected for manual double-throw switch operation. 


Explanation. —If both switches A and B are open, operating switch 
N will close B ; or operating switch M will close A. If both switches 
A and B are closed, operating N will open A ; or operating M will open B. 
If A is closed and B is open, operating N will open A and close B. If B 
is closed and A is open, operating M will open B and close A. Switches 
.4 and B cannot be simultaneously opened or simultaneously closed by 
MN. Therefore, if it is desired that both lamp-groups, C and D, be 
either lighted or extinguished at the same time, one of the switches, A or 
B, must be manually opened or closed. 

335. Automatic Double-throw-switch Operation Of Two 
Mechanically-held-closed, Remote-controlled Switches May 
Be Provided By A Relay as shown in Figs. 415 and 416. The 
relay so operates that if the regular service fails the load cir¬ 
cuit will be automatically connected to the emergency service. 
Then, if the power-supply of the regular service is re-estab- 







































Sec. 335] REMOTE-CONTROLLED CIRCUITS 295 

lished, the load circuit will be automatically reconnected 
thereto. Such an arrangement is sometimes used in theatres 
(Sec. 391) in connection with the emergency lights. The 
regular service (Figs. 415 and 416) is connected to a main or 
feeder of a public lighting company. The emergency service 
may be connected to either a storage battery, a continuously- 
operating isolated plant, another main belonging to the same 
lighting company, or to a main belonging to a different lighting 



Fig. 415.—Two remote-controlled switches so operated by a relay that if the regular 
service fails, the load will be automatically transferred to the emergency service. (Type 
F, Hart Mfg. Co.) 

company. As explained below, control of switches S i and S* 
(Fig. 415) from a distant location is not provided. By con¬ 
necting a double-pole snap-switch (D, Fig. 417) into the control 
circuit of Fig. 415, remote control of switches S i and $ 2 is 
provided as explained below. 

Explanation. —The operation of the remote-controlled switches 
of Figs. 415 and 416 is explained in Secs. 320 and 324, an understanding 
of which, will facilitate the tracing out of the circuits of Figs. 415 and 
416. As long as the voltage-supply of the regular service (Fig. 415) is 
maintained, current flows from C to D through the coil of the relay, R, 
and R is held in the position shown in full lines. If the voltage supply 
of the regular service is interrupted, the current through the coil of R is 
discontinued, and the contactor of R drops to the position indicated by 
the dotted lines. This closes the control circuits (see Sec. 320) of Si and 
S 2 thereby opening Si and closing S 2 . These control circuits are fed 
from the emergency-service circuit at A and B. Then, when the voltage 
































































296 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


of the regular service is re-established, R is again raised to the position 
indicated by the full lines. Thus S 2 is opened and Si is closed. 

In Fig. 417, connections are shown for controlling Si and S 2 from a 
remote location, D. By closing the double-pole switch ( D , Fig. 417), 
the lamps will, even though both the emergency and regular services are 
operative, be lighted from the regular service. If the regular service is 
inoperative, closing switch D will close $ 2 , and the current which is 



Fig. 416.—Double-pole, double-throw switch which is so operated by a relay that 
if the regular service fails the load will be automatically transferred to the emergency 
service. (Automatic Switch Co.) 


required for lighting the lamps will be supplied by the emergency service. 
Opening D will, if current is being supplied to the lamps from the regular 
service, extinguish them. But if D is opened while the current for light¬ 
ing the lamps is being supplied by the emergency service, the lamps will 
not be extinguished. As long as D is closed, the operation of the switches 
Si and S 2 will be identical to that explained above in connection with 
Fig. 415. 











































Sec. 335] 


REMOTE-CONTROLLED CIRCUITS 


297 


-Note. Two Tipe b Switches As Arranged For Automatic 
Double-throw Or Throw-over Operation by the Hart Mfg. Co. are 



Fig. 417. Two Diamond “H," Type F switches, with relay control for automatic 
transfer from regular service to emergency service, which have a double-pole switch, 
D, so connected into the control circuit that control of the switches Si and S 2 from a 
remote location is obtained thereby. (Remote-controlled switches are Type F, Hart 
Mfg. Co.) 



Fig. 418 .—Diamond “H" automatic throw-over swatch with relay control. (Hart 

Mfg. Co.) 


shown in Fig. 418. The circuit diagram for the same arrangement is 
shown in Fig. 419. The operation is identical to that explained above in 

















































































































































































































298 


LIGHTING CIRCUITS AND SWITCHES 


[Uiv. 8 


connection with Fig. 415. The contacts AA and BB (Figs. 418 and 419) 
are mounted at the sides of the switch frames. These contacts are only 
in circuit when the switch upon which they are mounted is open. Their 
purpose is to preclude the possibility of one switch closing before the 
other has opened. Their method of operation to prevent this may be 
understood from a study of Fig. 419. All wiring indicated by the light 
lines (Fig. 419) is provided and connected by the manufacturer, and is 
contained within the metal sub-base, E, Fig. 418. 



Fig. 419.—Circuit diagram of Diamond “H” automatic throw-over switch, showing 
condition of circuits when the load is receiving current from the regular service. 


336. Some Of The Various Methods And Devices Which 
May Be Used To Control A Remote-controlled Switch are 

suggested in Fig. 420. The load circuit which is served may 
be either a motor, M, or lamps, L. The energy for the control 
or operating circuit may be supplied either by: (1) The line, A, 
which serves the load. (2) Storage battery, B. (3) Generator or 
exciter, C. The operating circuit may be controlled by: 

(1) One or more two-circuit momentary-contact switches, S. 

(2) No-voltage release, V. (3) Overload release, 0. (4) Thermo¬ 

static regulator, T. (5) Time switch, D. (6) Pressure regula¬ 
tor, P. (7) Float- or tank-switch, F. When a device other 
than a momentary-contact switch is to be used to control a 
remote-controlled switch, the remote-controlled switch should 
be held closed mechanically, and should be of a type (Secs. 


































































Sec. 337] 


REMOTE-CONTROLLED CIRCUITS 


299 


320 and 325) wherein the control current is interrupted by 
the remote-controlled-switch mechanism. 



Fig. 420.—Showing general features and various methods and types of control which 
• may be applied to remote-controlled switches. (Hart Mfg. Co.) 


337. The Control Circuit Of A Remote-controlled Switch 
Should Be Protected By Fuses. To comply strictly with the 
Code requirements (Sec. 169), the control wires (Fig. 421) 







































































































300 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


should be fused at both A and B. However, remote-controlled 
switches for three-wire single-phase lighting service which 
embody a construction similar to that indicated in Fig. 422 
require only one fuse in the control circuit. That is, the wire 
(IF, Fig. 422) from the terminal which is connected to the ends 
of both coils, is connected to the permanently-grounded 



Fig. 421. —Showing method of fusing 
the control circuit of a remote-controlled 
switch to comply strictly with Code re¬ 
quirements. 


- + + 



L ? A fuse Momentary 

Contact Switch., 

lD C £ 


JL 


' Remote-Controlled Switch 
'Load 

Connection Common To Both Coils 


Fig. 422. — Showing a method of 
fusing the control circuit of a remote- 
controlled switch which may be per¬ 
missible for a three-wire single-phase 
circuit. 


Momentary 
Contact Switch-. 


neutral. This wire and the high-resistance coils are com¬ 
pletely enclosed, and are mounted on the slate base of the 
switch. Wire C is protected against grounds by fuse A. If 
wires D or E become grounded, no current could flow except 
when the momentary-contact switch was closed, and they 
(wires D and E) would then be protected by fuse A. The only 

possibility which would permit 
the continued flow of a heavy 
short-circuit current would be 
for one of the outside wires, 
L i or L 2 , to accidentally con¬ 
tact with wire W or with some 
part of the coil winding. The 
probability that this would ever 
happen is exceedingly remote. 
And if it should occur, the 
small wires which carry the short circuit current are enclosed 
and are mounted on a slate base. Consequently, only the 
switch would be injured, and no fire hazard would be incurred. 
The local wiring-inspection bureau should be consulted con¬ 
cerning its rules for the fusing of control circuits prior to 



Remote-Controlled Switch 


■ -Load 


Fig. 423.—Showing proper method 
of fusing the control circuit of a remote- 
controlled switch for a three-wire three- 
phase circuit. 
































































Sec. 338] REMOTE-CONTROLLED CIRCUITS 301 

their installation. Local rules might require a fuse at X and 
Y in Fig. 422. 


Note.—The Control Circuit Of A Remote-controlled Switch 
W hich Is To Be Used For Controlling A Three-wire Three-phase 
Circuit ShouldTIe Provided With At Least Two Fuses as indicated 
in Fig. 423. If fuse B is omitted, a ground on D or E might permit a 
current-flow which would be sufficiently large to incur a fire hazard. If 
the wiring MN (Fig. 423) is wholly within the switch, some inspection 
bureaus may require a fuse at X and one at Y. 

338. A Remote-controlled Switch Should Be Protected By 
Fuses in the same manner as is a manually-operated knife- 
switch. That is, the first fuse back of the switch toward the 
source of energy should have a rating not greater than the 
rated current-carrying capacity of the switch. See Div. 3 
for Code requirements relating to fuses and cut-outs. 

339. The Comparative Annual Costs Of The Two Systems 
Under The Given Conditions Should Determine Whether A 
Remote-control Or A Direct-control Lighting System Should 
Be Used. In general, the elements which determine these 
factors are: (1) The relative locations of the service entrance, 
the load center of the lamps, and the control locations. (2) The 
number of branch circuits which may be controlled from one 
location. (3) The number of control locations which is wanted. 
These elements are discussed in subsequent sections. 

Note.—The Annual Cost Of Either A Direct- Or A Remote- 
control System will be the sum of the fixed costs per year and the 
operating costs per year. The fixed costs per year include: (1) Insurance. 
(2) Taxes. (3) Interest. (4) Depreciation. The operating costs per 
year include: (1) Maintenance. (2) Attendance. (3) Energy loss. 
The costs of maintenance and attendance will usually be about equal for 
either a direct- or a remote-control system. The annual fixed costs will 
be determined by the first cost, which will in turn be determined by the 
allowable energy-loss cost. For example, assume that with a remote- 
control system, the first cost is higher than it is with a direct-control 
system. But with the direct-control system, the annual energy-loss cost 
is higher than it is with a remote-control system. Now, additional copper 
may be purchased for the direct-control until the annual energy-loss costs 
of the two systems will be equal. However, this would increase the first 
cost of the direct-control system, which would correspondingly increase 
the annual fixed cost of that system. Therefore, the minimum total 


302 


LIGHTING CIRCUITS AND SWITCHES 


[I)iv. 8 


annual cost of each of the two systems should be determined. Then, by 
comparison of the minimum costs of each, the system which incurs the 
least annual cost should be selected. (See explanation and examples ol 
the application of Kelvin’s law in the author’s American Electricians' 
Handbook. See also following example.) 

Example.—A current of 30 amp. is required for lighting the room of 
Fig. 424. The energy is supplied by a 110/220-volt, grounded-neutral, 
three-wire, single-phase system. The service entrance is located at E , 
the control location must be at C, and the distribution panel is located in 
the center of the room at P. The dimensions are as shown in the illustra¬ 
tion. Which would provide the more economical installation, a direct 
control or a remote control lighting system? All wiring is to be installed 
in conduit. 


K----- zoo'- -->) 

l ^.Control Location ) 



Fig. 424. —Illustrating method of determining the minimum total annual costs of a 
direct-control and a remote-control lighting system. 


Solution. —In the solution of such a problem certain values must be 
known or assumed, such as energy, labor, wire, conduit and switch costs. 
The solution which is presented below (scheduled in Table 340) and the 
values which are therein assumed are only intended to illustrate a method 
which may be followed in determining the most economical system. 
It is not intended to prove or disprove either system. Also, the assumed 
values must not be taken as applying to any particular installation. 

The general method of solution is to determine by computation which 
system is the least expensive—which has the least annual cost. Due to 
the fact that the total annual cost of either system varies for different 
conductor sizes, it is necessary to figure, for each of the two systems, 
this cost for several sizes of wire—all as shown in Table 340 and explained 
further on. As indicated in Column 4, Table 340, $47.68 is the minimum 
total annual cost which will be incurred by a direct-control system; this 
minimum annual cost results from the use of a No. 1 wire. As indicated 
in column 12, $27.64 is the minimum total annual cost which will be 
incurred by a remote-control system. Since the remote-control system 
















Sec. 339] 


REMOTE-CONTROLLED CIRCUITS 


303 


involves the smaller annual cost of the two systems, it would be the more 
economical and hence should be selected. The method of determining 
these annual costs is outlined below. 

The two propositions to be considered are (1) The direct-control system. 
(2) The remote-control system. If a direct-control system is used, three 
feeder wires and conduit for same must be run (Fig. 424) from E to 
C, and from C to P. There will also be required at the control location, C, 
an externally-operated, steel-box-enclosed, three-pole, non-fused, 30-amp. 
knife-switch. If a remote-control system is used, the following material 
will be required: Three feeder wires and conduit for same from E to P. 
One three-pole 30-amp. remote-controlled switch at E. Three No. 14. 
control wires and conduit for same from E to C and one two-circuit 
momentary-contact switch at C. The method of determining the mini¬ 
mum total annual cost of each system for a certain wire size will noAv be 
given. 

The assumptions which must he made for either the direct- or the remote- 
control system are as follows: Assume that the maximum allowable volt¬ 
age drop between E and P (Fig. 424) is 2 per cent. Then, the maximum 
voltage drop between E and P = 220 X 0.02 = 4.4 volts. By For. (35), 
p. 166, 2d Edition, American Electricians’ Handbook, cir. mils = 22 
X / X L -T- V, wherein: Circular mils is area of the conductor in circular 
mils. / = current in amperes. L = length, in feet, one way or single 
distance of the circuit. V = drop, in volts in the circuit. For a direct- 
control system (Fig. 434), L = EC + CP = 200 + 110 = 310 ft. 
I — 30 amp., and by solution above, V = 4.4 volts. Therefore, the 
minimum area of the wire in circular mils which will carry 30 amp. a 
distance of 310 ft. with a voltage drop of 4.4 volts = 22 X 30 X 310 -j- 
4.4 = 46,500 cir. mils. According to Table 170, the minimum size wore 
corresponding to 46,500 cir. mils, which will give a pressure drop not 
exceeding 4.4 volts will be a No. 3 B. & S. gage. Any wire larger than No. 
3 may from an electrical standpoint, be used; the problem is to determine 
what size wire is most economical. According to the Code (Table 170) 
a No. 8 wire could be used to carry the 30-amp. current. However, this 
would entail an excessive voltage drop. 

To illustrate the method of determining the total annual cost of a direct- 
control system for any given wire size, the following is worked out for a 
No. 2, B. & S. gage, wire. Assume that the knife switch located at C 
costs $15.00. Three wires from E to C to P (Fig. 424) would require: 
3 X 310 = 930 ft. of wire. At $101.00 per thousand feet of No. 2 wire, 
930 ft. would cost 101 X 930 -f- 1,000 = $94.00. Three No. 2 wires 
require (Table 176) a l/ 2 -in. conduit. According to Table 173, p. 546, 
American Electricians’ Handbook, 100 ft. of l^-in. conduit costs 
$27.50. Therefore, 310//. costs: 310 X 27.50 -*• 100 = $85.00. Accord¬ 
ing to Fig. 261, p. 639, and Table 356, p. 344 of the American Electri¬ 
cians’ Handbook, the cost of roughing in and of pulling three No. 2 wires 
in 310 ft. of l/£-in. conduit is about $59.00. Therefore, the total first cost 
of a direct-control system (Fig. 424) = 15 + 94 -f- 85 + 59 = $253.00. 


304 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


Assuming that the interest rate is 5 per cent.; depreciation, 4 per cent.; 
taxes and insurance, 1 per cent.; 5 + 4 + 1 = 10, or the annual fixed 
charges = 10 per cent, of $253 = 0.10 X 253 = $25.30 (see entries in 
Table 340). 

The energy-loss cost is computed as follows: The power-loss in any 
conductor is: P = PR, wherein: P = power-loss in watts. I = current 
in amperes. R = resistance of conductor in ohms. For this direct- 
control installation (Fig. 424), 7 = 30 amp. and since it is assumed that 
the grounded neutral carries no current, there will be (2 X 310) 620 ft. of 
No. 2 wire w r hich has a resistance of 0.16 ohms per 1,000 ft. Con¬ 
sequently R = 620 X 0.16 -T- 1,000 = 0.099 ohms. Then, P = 30 X 
30 X 0.099 = 89.2 watts which is the power-loss in the conductors. 
Assuming that the lamps are lighted 10 hr. per day for 300 days per year, 
the total number of hours per year which the lamps are lighted = 300 X 
10 = 3,000 hr. Hence, the annual energy loss in kilowatt-hours — 
3,000 X 89.2 -f- 1,000 = 268 kw.-hr. Assuming that the energy costs 
8 cts. per kw.-hr., the annual energy-loss cost = 268 X 0.08 = $21.44, 
which value is accordingly entered in Table 340 as shown. 

Assume that the cost of maintenance and attendance is $3.00 per year. 

Then the total annual cost of a direct-control system when using No. 2 
wire (Column 3, Table 340) = 25.30 + 21.44 + 3.00 = $49.74. The 
values for the other wire sizes for a direct-control system in Table 340 
are computed in a similar manner. 

The method of determining the total annual cost of a remote-control system 
(Fig. 424) for any given wire size is illustrated by the following: The 
same formulas and tables are used and the same general assumptions 
are made as above. The minimum area of the wire in circular mils which 
will carry 30 amp. a distance of 110 ft. with a voltage drop of 4.4 volts = 
22 X / XL t F = 22 X 30 XI10 4- 4.4 = 16,500 cir. mils, or a No. 8 
is the smallest size wire which can be used. 

The following example for a No. 8 wire (Column 9, Table 340) illustrates 
the method to be used in determining the total annual cost for any wire size 
for a remote control system . Assume that the remote-controlled switch 
and the momentary-contact switch cost $52.00. Then (3 X 110) 330 ft. 
of No. 8 wire from E to P at $17.00 per thousand feet costs: 17 X 330 -f- 
1,000 = about $6.00. And, (3 X 200) 600 ft. of No. 14 wire from E to C 
at $7.00 per thousand feet costs: 7 X 600 -4- 1,000 = about $4.00. Hence, 
the wire cost = 6 + 4 = $10.00. The three No. 8 wires require 110 ft. of 
1 -in. conduit , which at $17.00 per hundred feet costs: 17 X 110 -4- 100 = 
about $19.00. The three No. 14 wires require 200 ft. of f^-in. conduit , 
which at $8.50 per hundred feet cost: 8.50 X 200 -4- 100 = $17.00. Hence, 
the conduit cost is: 19 + 17 = $36.00. The installation of the conduit 
will cost about $34.00. Therefore, the total first cost of a remote-control 
system using No. 8 feeder wires = 52 + 10 + 36 + 34 = $132.00, as is 
entered in Table 340. Whereupon, the annual fixed charges = 132 X 
0.10 = $13.20. The energy-loss cost = 3,000 X 7 2 X R X 0.08 -4- 1,000 
= 3,000 X 30 X 30 X 0.14 X 0.08 = about $30.40. Assume that the 


Sec. 339] 


REMOTE-CONTROLLED CIRCUITS 


305 


cost of maintenance and attendance is $3.00 per year. Then, the total 
annual cost of a remote-control system (Fig. 424) when using No. 8 wire is: 
13.20 + 30.40 + 3.00 = $46.60. 

To determine which is the most economical system , first select the size of the 
wire for the direct-control system which involves the least annual cost 
for that system; this, in this example, see Table 340, is No. 1 wire, total 
annual cost $47.68. Then, select the size of the wire for the remote-control 
system which involves the least annual cost for that system; this, in 
this example, see Table 340, is No. 00 wire, total annual cost $27.64. 
Then that system of the two selected as above which involves the 
smaller total annual cost should be used; obviously, in this example, the 
remote-control system using No. 00 wire with a total annual cost of 
$27.64 is the most economical. 


20 


340. Table Showing Comparison Of Annual Charges On Direct-control And Remote-control 
Wiring Systems. See Fig. 424 for diagram. Energy costs 80. per kw.-hr. Distances are as shown in 
Fig. 424. Labor at $7.00 per day. 


306 


LIGHTING CIRCUITS AND SWITCHES [Div. 8 


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•Sec. 341J 


REMOTE-CONTROLLED CIRCUIT'S 


307 


341. Where The Load Center, The Service Entrance And 
The Control Location Must Be Separated By A Considerable 
Distance, A Wire-saving May Be Effected By The Use Of 
Remote-controlled Switches as shown in Figs. 425 and 426. 
The control location, A, the service entrance, B, and the 
load center, C, have the same relative locations in Figs. 425 


B 




ZZSU2 


3H~g~ 






T=- 


XL 


Approximate Load Center.. 


'■-.660-Watt branch 


. 


\4> 


A ,T hree Single-Pole Switches 

On First Floor .. . .... 

(One for Each Branch) ThrK * 4 W,ra 


JJ 


Service entrance 
In Basement-.. 


"Distribution Panel In Basement 


150 



<\> 


Fig. 425.—Direct control system. 


and 426. It is assumed that A and B must be at the locations 
shown. In Fig. 425, the control, A, of each of the 660-watt 
branches of the load-circuit is provided by a single-pole 
switch. Therefore, the distribution panel, P, is located as near 
to A as is feasible. Then, three large wires (each of which 
should, for this installation, be about No. 4, B. & S. gage) 



Three No. 14 Control Wires From A To B - ' 
. -150 .. 


Fjg. 426.—Remote-control system. 


would be required between P and B. By using a remote- 
controlled switch to control the three branch circuits, as in 
Fig. 426, three No. 14 wires will be required between A and B. 
Therefore, if the distance from the control location A to the 
service entrance B is, say, 150 ft., the wire-saving which will be 
effected by the remote-control system over the direct-control 














































308 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


system will be the difference between 450 ft. of No. 4 wire and 
450 ft. of No. 14 wire, which is about 50 lb. of copper. 

Note. — If It Was Desired To Arrange The Control Of Fig. 426 
So That Each Branch Could Be Lighted Or Extinguished Sepa¬ 
rately, then three remote-controlled switches would be required at B , 
three two-circuit momentary-contact switches would be required at A, and 
seven (see Fig. 408) No. 14 control wires would be required between A 
and B, if a common-return was used. If a common-return wire was not 
used, then nine control wires would be required between A and B. 
In such cases the remote-control system might not be justified. 

342. A Remote-control System May Be Used For Those 
Installations Where It Is Desired That The Lamps On A 
Large Number Of 660-watt Branch Circuits Be Simultane- 



Fig. 427.—Remote-control installation for controlling all circuits on one floor. 
(This is especially applicable where the service entrance, E, and the riser, R, are at one 
end of the building and where it is desired that the control location, S, be near the eleva¬ 
tor shaft or stairway at the other end of the building.) 

ously Lighted And Extinguished (Fig. 427). This system is 
especially desirable where the control location, S, which is 
provided by the momentary-contact switch is at a great dis¬ 
tance (Fig. 427) from the distribution panel (Fig. 428). Even 
if the control-location (S, Fig. 427) was near the distributing 
panel, P, a remote-control system might be preferable to a 
knife-switch direct-control system because of the following 
reasons: If a knife switch which carries a large current is 







































































>Sec. 343] 


REMOTE-CONTROLLED CIRCUITS 


309 


1 requently operated by inexperienced persons, severe arcs 
may be drawn which will damage the switch and may, if the 
switch is not of the externally-operated type (Fig. 140), injure 
the operator. 


660-Watt Branches. 



Fig. 428. A three-wire to two-wire distribution panel controlled by a remote-controlled 

swatch. (Hart Mfg. Co.) 


343. A Remote-control System Will Frequently Provide An 
Economical Installation For Multi-location Control Of A 
Large Number Of Lamps. The distribution panel may be 
located in the most desirable place with reference to available- 
space and load center considerations. The control locations 
are provided by two-circuit momentary-contact switches 
which are wired according to Fig. 406 or Fig. 40cS. 

Example. —In Fig. 429, the distribution panel, D, for the auditorium 
lights and for the stage lights of a small moving-picture theatre is located 
on the stage. Four momentary-contact switches are used to control the 
lights: Two for the stage lights and two for the auditorium lights. One 
of the switches, W, for controlling the stage lights and one, X, for con¬ 
trolling the auditorium lights are located in the lobby. The other two 
switches, Y and Z, are located in the picture-machine booth. Hence, 
both the stage and auditorium lights may be controlled from either 
the picture-machine booth, or from the lobby in the front of the house 
(see also Div. 9). 





































































310 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


Example. —In Fig. 430, the lamps of a large ceiling fixture, such as 
that frequently used in churches, are controlled by a remote-controlled 
switch. Where sufficient space is available to provide access thereto, the 



Fig. 429.—Remote-control system for controlling the stage and auditorium lights of a 

small moving picture house. 


remote-controlled-switch distribution panel may be installed between the 
ceiling and the roof in close proximity to the dome fixture. As many 
control locations as desired may be provided by momentary-contact 


.Feeders From Main Distribution 
•'! Pane! At Service Entrance 



1' ig. 430. Remote-controlled switch, installed between ceiling and roof, to control 

lamps in a large dome fixture. 

switches connected as shown in either Fig. 406 or 408. This method 
tends to decrease the cost of wiring because it shortens the branch circuits. 





























































































Sec. 344] 


REM0 TE-CON TROLLED CIRC UITS 


311 


344. Electrically-held-closed, Single-pole, Remote-con¬ 
trolled Switches May Be Used To Control Lamps In Moving- 
picture Studios. (Electrical South, July 1921; p. 24.) Each 
of the remote-controlled switches ( R , Fig. 431) which are 
located overhead, control an arc-lamp circuit. The single-pole 
switches, S and M , and the three-way switches, T, are mounted 
on a portable base and connected as shown in Fig. 431. 
Mounting the remote-controlled switches overhead prevents 
the heavy cables from being scattered about the floor. A 
constant source of danger to the studio workmen is thereby 
removed. As explained below, the portable switch-box, B, 



Fig. 431.—Showing how a remote-control system may be adapted to the control of arc 

lamps in a moving-picture studio. 

may be placed beside the camera-man or director, so that he 
may, at all times, have absolute control of the lights on the 
scene. 

Explanation. —The usual practice of controlling the lights for a scene 
was to station a man at the studio switchboard, who, upon a given signal, 
closed the switches to the lamp circuits to be lighted. These signals 
frequently miscarried so that when the actor entered the room and 
apparently operated a wall switch, the room did not light. Then the 
scene had to be retaken. With the remote-control system this error will 
not occur. 

Assume that a certain scene opens with a ‘'dark room” effect. Suffi¬ 
cient light for this effect is provided by the arc lamps which are controlled 
by R 2 (Fig. 431). The director sets switches S 2 and T 2 (Fig. 431) in the 
positions shown. This closes R 2 and lights the proper lamps. A little 
later the actor is to enter the darkened room and grope about until he 















































































312 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


locates the wall switch which is supposed to control the electrolier fixture 
of the room. The director sets Si, T\, S3, Tz, S 3 and T$ in the positions 
shown. As the actor finds the wall switch in the darkened room, the 
director closes the master switch M. This simultaneously closes the 
remote-controlled switches, Ri, Rz, and R&. The illusion of the actor 
lighting the room is maintained as follows: Ri controls a baby arc which 
is concealed in the lamp sockets of the room chandelier. R 2 controls 
several flood lights which illminate the entire room. R 6 controls a number 
of spot lights which bring out the features and expression of the actor. 
Since S 4 and S 5 are left open, the lamps which are controlled by R 4 and 
Rz are not lighted. 

345. The Master Switch For Controlling A Master Circuit 
In A Residence Or Other Building May Be A Remote-con¬ 
trolled Switch (Fig. 432). The same general rules as outlined 



Chandelier 


3 Ampere 
'''Fuse 

; ) i'W 


Chandelier 


,—i—, Momentary 
a Contact 

■ - r m i 


Three- Way 
Switch- 


Three-Way 
Switch- 


^-Switch 


Master's Room 


Second Story 


-Chandelier 


Chandelier 


Three-Way 

Switch-' 


Three■ Way j 
Switch 




3FJ * Mains 
i. ! Switch 
$$ 'CutOut 


MeterI 


1 Remote Control Switch 'Three - Way Switch 


Basement 


Concrete 


Service 

Wires 


Fig. 432.—A remote-controlled switch used to control the master circuit in a small 

residence. 


in Div. 6 in regard to the interconnection of branches and 
the number of poles required for the master switch must be 
observed. As explained below, such use of a remote-controlled 
switch will not ordinarily be justified in medium- and small¬ 
sized residences. However, in large buildings which have 



















































































Sec. 346] 


REMOTE-CONTROLLED CIRCUITS 


313 


several branch circuits, the installation of a remote-controlled 
master switch may (Sec. 346) be advisable. 

Explanation. —Number 14 wire will ordinarily be large enough for the 
branch circuits and for the master wires in small- and medium-sized resi¬ 
dences. Also, No. 14 wires are required for the control of a remote-control¬ 
led switch. Therefore, for such installations, the use of a remote-controlled 
switch does not generally effect a wire-saving. In Fig. 432, assume 
that the remote-controlled switch, R and the momentary-contact switch 
M and the control-circuit wires, A, B, and C, are removed. Control 
of the master circuit may then be provided as follows: (1) Install a 
single-jpole snap-switch at M. (2) Connect M into the circuit with No. 14 
wires as indicated hy the dotted lines at W . Thus, by using a direct- 
control system (Div. 6) for the master circuit instead of a remote-control 
system, a considerable saving is effected. 

346. A Remote-controlled Master Switch For Master 
Circuits Of Large Residences Or Other Buildings is shown in 
Fig. 433. Switches of this type are made with from 8 



Fig. 433.—Remote-controlled, multi-circuit switch for the control of a master circuit. 

{Hart Mfg. Co.) 


to 20 poles. The wiring diagram of an 18-pole switch 
used to master 18 branch circuits is shown in Fig. 434. As 
explained in Sec. 291 in connection with Fig. 337, single-loca¬ 
tion control of the lamp-groups may, if there is only one lamp- 
group on each branch circuit, be provided by single-pole 
switches. The use of such a remote-controlled master switch 










































































































































314 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


may effect a large saving over direct-controlled master switches 
in those installations where several branch circuits are to be 



Fig. 434.—Wiring diagram of a multi-pole remote-controlled master switch. (Since 
each branch circuit has connected to it only one lamp-group, a single-pole switch may 
be used for single-location control of each lamp-group.) 


mastered and where several master-switch-control locations 
are desired. 



Fig. 435.—Circuit diagram of a combined remote- and direct-control system for a master 
circuit arranged to operate in conjunction with a fire-alarm system. 


Note.—A Circuit Diagram Of A Combined Direct- And Remote- 
control System For The Master Circuits Of A Large Building is 
shown in Fig. 435. One pole of the double-pole master switch, M, 
provides direct-control of a master circuit. By arranging this master 


































































































































































Sec. 347] 


REMOTE-CONTROLLED C1RCU1TS 


315 

circuit as explained in Sec. 291, several lamps may be directly mastered 
therebj r . The other pole of M controls the circuit of the 120-volt relay, 
R. Closing R causes the electrically-held-closed remote-controlled 
switch, S, to close, thus lighting the three-location-controlled hall-and- 
stairway lamps, L. If the residence is a three-story building, and has a 
three-location-controlled lamp-group for each floor, a three-pole, electric- 
ally-held-closed switch may be used at S and each pole connected to each 
lamp-group. The building may also be provided with a fire alarm which 
is so arranged that sounding the fire alarm (Fig. 435) will light the hall- 
and-stairway lamps of each floor. If any single-pole switch, F, is closed 
to ring the fire-alarm bells, relay, V, then operates and closes the control 
circuit of S, and all of the hall lamps are lighted. 

347. Table Showing List Price And Standard Ratings Of 
One Type Of Sundh Remote-controlled Switches (Bulletin 
7,200, p. 2, Sundh Electric Co.). In January, 1922, a maximum 
discount of 33^ per cent, applied to the following quotations: 


Volts 115-230 Direct Current or 110-220-440 A.C. 60 Cycles or less 


Ampere 

1 Pole 

2 Pole 

3 Pole 

4 Pole 

30 


$ 35.00 

$ 40.00 

$ 54.00 

60 


45.00 

50.00 

81.00 

100 


75.00 

90.00 

162.00 

200 


112.00 

131.00 

225.00 

300 

$135.00 

144.00 

162.00 

288.00 

400 

153.00 

166.00 

216.00 

333.00 

500 

194.00 

207.00 

261.00 

423.00 

600 

212.00 

243.00 

306.00 


800 

248.00 

275.00 

350.00 


1,000 

293.00 

311.00 

387.00 


1,500 

338.00 




2,000 

450.00 

Prices on 

other sizes upon request 

2,500 

562.00 





When Ordering: 


For Direct Current, give capacity of switch, 
number of poles and voltage of circuit. 

For Alternating Current, give capacity of switch, 
number of poles, and exact voltage and frequency of 
, circuit. 


Note.—A lthough the above table is not intended to contain the prices 
or ratings of all remote-controlled switches, the values contained therein 
are probably, in general, typical for other makes and types. 






































316 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


348. A Method Of Controlling Signs By Remote-controlled 
Switches is shown in Fig. 436. The Topeka {Kan.) Edison 
Company operated a number of flat-rate signs. These were 
switched “on” at dusk and “off” at 10 o’clock, except on 
Saturday night, when they were burned until 11:30 p. m. 
When controlled and switched by hand, as formerly, the com¬ 
pany received the usual complaints because one sign was 
turned on or off before another as the patrolman progressed 
on his rounds. This previously-unavoidable dissatisfaction 
ceased with the installation of the remote-control system 



Fig. 436.—Remote-controlled switches controlling flat-rate signs. 


which is shown and the wage of the patrolman, $20 per month, 
was saved by this switching of all the signs from a central 
point. A remote-controlled switch was installed at each sign. 

Explanation. —Shell-type electromagnets, M, were used in the 
remote-control switches. The outer dimensions of the iron magnetic- 
return casing were 4 in. long by 3 in. in diameter. The iron plunger, P, 
had 1-in. travel in the 1-in. brass tube in which it slides. Two and one- 
third pounds of No. 25 black enameled magnet wire were used in each 
coil. A brass rod, B, connected the plunger with the leaf-spring contac¬ 
tors, C, which were supplemented by carbon-break blocks which “take” 
any arcs that form on breaking the circuit. J. E. Gossett , electrical 
foreman, who laid out the scheme, estimated the cost of these magnet 
switches to be about $6 each. 

Extending through the business district is a No. 10 iron wire, W, which 
is used as the pilot circuit and is tapped in multiple to the remote-control 
magnet windings. Each magnet coil has a resistance of about 110 ohms 
and at 110 volts takes 1 amp. which closes the contact effectively. A 
current of less than 1 amp. will hold the plunger in the closed position. 













































Sec. 349] 


REMOTE-CON TROLLED CIRCUITS 


317 


Hence, at the control location there is a resistor R of a predetermined 
resistance (110 ohms) which can, by opening switch H, be inserted in the 
pilot circuit after the remote-controlled switches have been closed. This 
reduces the current per coil to 0.5 amp., which is ample to hold the 
contacts in position. To light the signs, the controlling switch, S, is 
closed (the resistance switch, H, having already been closed); thereby 
current is permitted to flow through the remote-controlled switches. 
Switch H is then opened, thereby inserting resistance R into the circuit 
to cut the holding current down to normal value, so that the magnets 
will not heat. Fifteen large signs were operated by the Topeka pilot- 
wire circuit, which was nearly a mile in length. 

349. A Method Which Has Been Employed For The 
Remote Control Of An Alternating-current Series Incandes¬ 
cent Lamp Circuit is shown diagramatically in Fig. 437. 
The Worcester (Mass.) Electric Light Company installed a 


r 

2,300- Volt, A. C. Circuit 






u" A v 



r~ x x 

D. C. Arc 
Circuit 

s j 

—: -i 

rw- 

4 

T> ] 

f V ' 1 

'■‘.■Fuse 

Incandescent Lamp Circuit---, 

i (S: ' > -L , ■ v f 

-J- Q - Q - O - & • Q - —o -6 


Solenoid Switch — . V -Constant Current Transformer 


Fig. 437.—Remote control of a series incandescent lamp circuit. 

number of trial 4 amp., 75 watt alternating-current tungsten 
series incandescent lamp circuits, L, early in 1912, for the 
street illumination of outlying districts. To economize 
in the feeder investment for this work, Fred II. Smith, superin¬ 
tendent of the company, devised the plan which is shown by 
which energy for the operation of each circuit is derived from 
the regular 2,300-volt, single-phase commercial feeders of the 
plant. 

Explanation. —Each circuit of series incandescent lamps contains 
from 50 to 75 lamps looped through a suburban zone. Each 
circuit is fed from a constant-current transformer, PS, located in a pole 
box in the immediate neighborhood of the lamp district. The constant- 
current transformer is connected across the 2,300-volt line. One side 
of the primary of PS is fused and the other side connected through a 
solenoid switch, S. The actuating coil of the solenoid switch, S, is in 
series with one of the company’s direct-current series street arc-lighting 
circuits which passes the location of the transformer. 
























318 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


The series incandescent lamp circuit is switched on automatically at the 
time the direct-current arc service is switched into operation: The 
closing of the d.c. arc circuit at the station lights the arc lamps, A, and 
simultaneously permits current to pass through the solenoid switch coil 
in the pole box. This closes the contacts of the local constant-current 
transformer primary, P, and lights the series incandescent lamps, L. 
In order to keep the alternating-current incandescent circuit constantly 
in service, regardless of the current fluctuations and regulation of the 
direct-current arc-lamp circuit, a pole piece is installed in the core of 
the solenoid switch. This pole piece is so designed that the plunger of the 
switch is drawn firmly against the pole piece at the instant current first 
passes through the arc circuit and coil of switch S. Even if no direct- 
current passes through the coil of S, the residual magnetism of this pole 
piece is sufficient to hold the plunger up against the pole piece. In the 
morning when the direct-current arc circuit is cut off, the incandescent 
service remains on until an operator at the distributing substation permits 
alternating current to flow through the d.c. arc circuit. This demagnet¬ 
izes the solenoid core which permits the plunger to drop and open the 
series incandescent circuit. The solenoid switch is of the oil type. 

Fourteen alternating-current incandescent circuits arranged as described 
were in operation at Worcester. The loads on the different circuits vary 
from 4 kw. to 10 kw. The effect upon the 2,300-volt lines has been 
negligible. By the use of the automatic switch, S, which is built for 
high-potential operation, no patrolman is required to switch the series 
incandescent lamps on and off. The arrangement has saved money in 
underground conduits, ducts and feeders, besides rendering unnecessary 
a switchboard at the main distributing center. 

350. Remote Control Of Street Lamps Which Are Fed 
From An Edison System is illustrated in Fig. 438. This 
arrangement was used in the business section of Dayton, Ohio, 
which was lighted by 360, 340-watt tungsten clusters, divided 
into seven sections, three of which are shown. Each section 
was fed at a convenient point from the 220-volt Edison three- 
wire mains ( M , Fig. 438) of the Dayton Lighting Company. 
Formerly controlled by hand from street switches, this light¬ 
ing when arranged as shown can all be manipulated practically 
simultaneously from the station switchboard, AB. The 
magnet-switch scheme which is shown requires considerably 
less wiring than is necessary for the usual distribution or for 
pilot-wire controls. The scheme was developed by 0. IT. 
Hutchings, general superintendent of the company. 

Explanation. —Closing one of the control switches, A or B, (Fig. 438) 
energizes the magnet contactor, C h of a nearby section. As this section 


Sec. 350j 


REMOTE-CONTROLLED CIRCVITS 


319 


lights up, it in turn energizes the contactors, C 2 , of section No. 2. The 
action is similarly repeated throughout the system, until the lighting of 
the last section is indicated by the pilot lamps, L, on the switchboard. 
One switch B, thus controls the four lower 60-watt post lamps which are 
operated till midnight; the other switch, A, governs the single 100-watt 
post lamps which are operated all night. Although this is not shown in 
the sketch, each section is balanced on the three-wire system, double-pole, 
switches being used instead of the single contacts, C, which are indicated 
in Fig. 104. Individual sets of these 100-amp. General Electric carbon 
break contacts are mounted, with the section fuses and meter, in a 30-in. 



Fia. 438.—Remote control of street lamps which are fed from an Edison three-wire 

system. 


by 34-in. gasketed man-hole box which is installed at the feeding point 
of each section. The meters are read monthly and the switches are 
inspected and cleaned at this time. Each magnet winding takes about 
0.3 amp. at 110 volts in its holding position, and the contacts carry 58 
amp. to 90 amp. 

From the instant that the control switch is closed to that at which the 
corresponding pilot lamp flashes, barely one second elapses. Hence this 
is the time required for the impulse to traverse the seven switches and a 
total distance of 10,500 ft. Half of this path is in the No. 12 pilot-wire 
circuit. The average length of the pilot circuit is 785 ft. The system 
cost $120 per switch station to install, exclusive of meters. It saved 
about one-half hour’s daily operation, due to irregular lighting, or about 
















































320 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


(30 kvv.-hr. per day, in addition to labor. Half a mile from the nearest 
post-lighting circuit, the Dayton company also lights a bridge with 
alternating-current multiple tungsten lamps. The control of these has 
been effected by extending a pilot circuit and magnet switch from the 
direct-current curb system, replacing a time switch which was formerly 
used at the bridge. The cost of operating the curb system was $55 per 
340-watt post per year. 

351. Another Method Of Remote-control Operation Of 
Ornamental Street Lighting is illustrated in Fig. 439. The 
arrangement was used in Peoria, Ill. where 240 five-lamp stand¬ 
ards were employed to light the downtown section of the city. 
The five-lamp standards are fed in groups of six from the 



Fig. 439.—Remote control of ornamental street lighting system in Peoria, Ill. 


110/220-volt alternating-current three-wire mains. They 
are switched on and off by means of a remote-control pilot 
circuit (Fig. 439) which operates relay switches at the feeding 
points. With a step-by-step mechanism the four 60-watt 
lamps or the single 100-watt lamps on each 5-lamp standard 
may be turned positively on and off, independently of the 
others. Only a single control wire is used. 

Explanation. —At each feeding point for a six-post group, a relay 
switch (Fig. 439) is installed in a post base. The switch includes a 
1,000-ohm telephone relay, R, bridged between the control wire, C, and 
the system neutral, and the 50-ohm switch magnet, M, the winding, W, of 
which is energized through the relay contact. This operating magnet, 
W, works against the switch shaft, rotating it 90 deg. each time the mag- 










































































Sec. 351] 


REMOTE-CONTROLLED CIRCUITS 


321 


net is energized. Pitman rods which extend from this shaft, control 
contacts dipping into the two mercury cups of the switch. One cup is 
for the top-lamp circuit and the other is for the four lower lamps. The 
crank pins for these rods are also quartered 90 deg., as Fig. 105 shows, 
so that in succession both contacts may be down, or one up and one down, 



Fig. 440.—Oil switch which is remotely controlled by a small three-phase motor. 


or both up. This series of positions is passed through in the course of 
one rotation, lighting first the lower lamps, then the top lamps, then 
extinguishing the lower lamps and finally extinguishing the top lamps. 

Some difficulty was at first experienced in timing the impulses to 
operate all the relays and switches positively, but the messenger call-box 
mechanism, B, which was finally adopted, solved this 
problem. The current impulses in the control wire, C , 
are, by B, each maintained at about 15-sec. duration with 
a 5-sec. interval between each impulse. Another slight 
source of trouble was due to the sensitiveness of the 
relays as they were first installed. A heavy blow on 
the lamp post, such as that caused by a wagon riding 
over the curb, would cause a momentary closure of the 
contact, throwing the control circuit of that post out of 
step. But these minor difficulties were speedily cleared. 

Each switch, before being installed, received a test of 
500 operations without a single failure. Each switch 
mechanism is inclosed in a 6-in. by 10-in. iron box, 2 in. 
deep, which has fiber entry bushings for the wires. Each 
outfit cost about $12, as made in a local shop. The No. Fig. 441.—Self- 

10 control wire, C, which operates the forty switches has restoring push- 
a total length of about 3 miles. Each relay takes about 
0.1 amp. and the operating magnets 2 amp. momentarily. Electric Co.) 

C. A. Rich, foreman of the underground department 

for the Peoria Gas & Electric Company, devised the installation 

described. 

Note.—The Remote Control Of Either Primary Or Secondary 
Circuits May Be Provided By Means Of A Small Motor (By D. E. 


Porcelain 



21 



























322 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


King) as shown in Fig. 440. The three-phase motor, M, is fed from a 
No. 14 wire at a potential of 220 volts, the distance from the office to the 
switch being a quarter of a mile. The oil switch, 0, connects the 2,300- 


^ ■ - Door Switch -Pivot 




—Q- 

V 

Spring. ' 

r 

- 

X 



Lamp- 

To Branch- 

% 


To Branch--' 



A - Switch Closed 



B- Switch Open 


I-Lamp Lighted When Door Is Open And Extinguished When 
Door Is Closed 


S 


-O 


To Branch - 


A'Switch Closed 



I-Lamp Lighted When Door Is Closed And Extinguished When 
Door Is Open 


Fig. 442.—Door-switch circuit-diagrams. 



Fig, 443.—Door switch installed in the 
door jamb of a closet so that the circuit is 
closed when the door is opened. 



Fig. 444.—Showing a door switch in¬ 
stalled in a door jamb and the method of 
securing an armored cable to the switch 
box. ( Catalog Nos. 7240 and 7241, Cutler- 
Hammer Mfg. Co.) 


volt primaries with two constant-current transformers, used for series 
street lighting. To throw the circuit on or off, reverse the direction of 
rotation of the motor. To effect this a two-pole, double-throw switch S 






























































































































































Sec. 352] 


R E MO TE-CON TROLLED Cl RC U l TS 


323 


is used. The center leg ol the motor is always in circuit and when the 
switch is thrown in one position two of the phases are reversed. In the 
other position the connections are normal. 

352. A Door Switch May Be Installed In The Door Jamb 
So That Opening And Closing The Door Operates The Switch. 

Switches of this type (Fig. 441) are made (Sec. 95) so that the 
circuit (Fig. 442) may either be opened or closed by closing the 



Fig. 445.—Solenoid door-bolt switch for automatic control of lights in hotel rooms. 
This switch sets in the door jamb. (Ilart Mfy. Co.) 


door (Fig. 443). Door switches which are so designed that 
the lamp is lighted when the door is open and extinguished 
when the door is closed are suitable for installations in clothes 
closets, linen closets, entrance halls, vaults, and the like. 
Door switches which light the lamp when the door is closed 
and extinguish it when the door is open are used principally 
in telephone booths, toilets, and the like, where one would 
naturally close the door after entering. A method of fastening 
armored cable to a door switch is shown in Fig. 444. 












































324 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


353. The Solenoid Door-bolt Switch (Figs. 445, 445A, 445#, 
and 446) is used principally in hotel guest-rooms to effect a cur¬ 
rent-saving. It is so operated by the bolt in the door lock that 
when the guest leaves the room and locks the door any lamps 
which he may have left burning therein will be extinguished. 
A separate bolt is used to lock the door from the inside. This 
inside locking bolt does not operate the switch. One manu¬ 
facturer of such a switch estimates that the cost of the current 



Button 
Operated 
■ By Lock 
^ Bolt 

V 

Magnet 
Winding 



I-Sec+ionod Elevation (Prongs 
L And H Omitted From This View) 



E-Partial Sectional 
Elevation 


Fig. 445 A .—Mechanism of Hart Mfg. Co’s. Type D magnetic door-bolt switch. (A 
sectional elevation is shown at I, and a partial sectional elevation at II. As shown at 
I, the door has just been unlocked from the outside, permitting contactor plate F to 
drop down and touch the two contact points, E, only one of which is show T n. This 
completes the circuit through the magnet, which immediately raises the core B to that 
position shown at II, thus closing the main switch S. When S closes, the lug C is 
pulled into the notch N by a spring. When C is pulled into N, C engages with another 
lug G, and raises F off the two contacts E. Thus, the main switch is closed and the 
electromagnet circuit is opened, thereby permitting the lamps to be controlled from the 
inside of the room by the room switch. When the occupant leaves the room and locks 
the door from the outside, the button A is pushed in. This causes the cam surface, L, 
to strike and raise the prong H. Thereby C is disengaged from N and the main switch 
S drops open. Also when A is pushed in and the main switch is opened, the under 
side of M (in I) holds prong P down so that F cannot touch E. Thus the electro¬ 
magnet carries no current while the switch is open or closed. The only time the 
electromagnet carries current is for an instant after the door is unlocked from the 
outside.) 


which will be saved by its use will pay for the switch in about 
18 months. That the switch will operate to save current is 
based on the assumption that a hotel guest is more likely to 
lock the door when he leaves the room than he is to turn off the 




























































































































Sec. 353] 


REM 0 T E-CON TROLLED CIRCUITS 


325 



I-Fron+ Elevation 


Itt-Sid e Elevation 


Fig. 4455. —Installation of door-bolt switch. (Hart Mfg. Co.) 


























































































































































326 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


lights. The operation of the switch is explained below. The 
usual rating of door-bolt switches is 3 amp. at 250 volts, or 
6 amp. at 125 volts. 

Explanation. —When the door is locked from the outside, the lock 
bolt, L, passes into the strike and operates the switch button ( B, 
Figs. 445, 446, and 447) so that the contactor (C, Figs. 445 and 447) is 
raised off of the pilot contacts (P, Figs. 445 and 447). Therefore, when 
the door is not locked from the outside—occupant is within the room— 



Fig. 446.—Solenoid door-bolt switch installed in door jamb. (Hart Mfg. Co.) 

the solenoid (E, Figs. 445 and 447) will be energized by a very small 
current-flow from X to Y. This raises and closes the single-pole switch, 
F, which is connected in series with one side of the line. Then, the 
lighting and extinguishing of the center lamps may be controlled by 
operating the single-pole room switch (G, Fig. 447). The bracket and 
toilet lamps may then be controlled by their respective key sockets. 

When the occupant leaves the room and locks the door, the electrical 
connection between the pilot contacts, P, is as explained above, broken. 
Solenoid E is thereby de-energized and the switch F drops downward to 
the open position. This opens one side of the line. Consequently 
any lamps within the room which may have been left lighted are extin- 

































































































Sec. 354] 


REMOTE-CONTROLLED CIRCUITS 


327 


guished when the door is locked. Then when the door is unlocked from 
the outside, those lamps which were left on when the occupant departed 
will be automatically relighted. 

Note.—The Maximum Instantaneous Current Taken By The 
Solenoid of the Hart switch is 1.2 amp. These values are for 110-volt 
switches. 


/ Bracket And Toilef Lamps button 
; (Controlled By Key-Sockets) Operated 

Center Lock Bolt 
Lamps [ ContactorT 




Single-Pole 
5 witch If 
Desired 


Fig. 447.—Explaining operation of a solenoid door-bolt switch. 


354. Various Circuit Diagrams For Solenoid Door-bolt 
Switches are shown in Figs. 447,448,449, and 450. An instal¬ 
lation connected according to any of these diagrams will, as ex¬ 
plained in preceding Sec. 353, operate to extinguish all of the 


Bracket Lamps- 


rr 


V> 

! 


I 

£ 


o 

-o- 

-©■ 


-y£)~ 

-o~ 

■-v>- 


V 


in 

f n 

*9* 

Ip- 

of 


J j 


J L 

w 


Line 

± 


'..Center Lamps 

-Single-Pole 
Room Switches 


By Lock Bo/f^ 



Door-Bolt: 
Switch- 1 ' 


A 


Bracket 

Toilet 

Lamps 


Single-Pole 
Switch If 
Desired 




Line.:? 

± 


Center 
< '"Lamps 


r' 


...■Double-Pole 
Room Switch 

-Solenoid Vi ire 

Button Operated 
By Lock BoLt— -^ 



Door-Bolt Switch 

+ 


Fig. 448. Fig. 449. 

Fig. 448.—Circuit diagram of solenoid door-bolt switch for controlling room lights 
with two or more single-pole room switches. (Hart Mfg. Co.) 

Fig. 449.—Circuit diagram of solenoid door-bolt switch for controlling all lights with 
one room switch. (When G is open, F is open. When G is closed S will be closed if the 
door is not locked from the outside. When the door is locked from the outside, F is 
open. Hart Mfg. Co.) 


lamps within the room when the door is locked from the outside. 
In Fig. 449, a double-pole room switch, G, is used. The 
















































































328 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 



Fig. 450.—Hotel-room solenoid door-bolt switch installation. This corresponds to 
the circuit diagram of Fig. 447. A double-pole room switch connected as indicated in 
Fig. 449 is preferable. 



Fig. 451. —Showing a door-bolt switch installed in the door jamb with wood screws. 
They can also be mounted on the strike by using spacers and machine screws furnished 
with the switch or directly on the back of a box strike without the spacers. Two holes 
are tapped in the switch plate for the screws. The drilling of the strike is as shown. 
{Cutler-Hammer Mfg. Co., List No. 7242.) 

































































































































































Sec. 354] 


REMOTE-CONTROLLED CIRCUITS 


329 


solenoid wire is connected to a point which is behind G. 
Therefore, when G is open, no current can flow through the 
solenoid. Thus, all of the lamps within the room may be 
controlled by G, because when G is opened, the solenoid is 



Fig. 452.—Circuit diagram of single-pole door-bolt switch which is directly operated 
by the lock bolt. Two single-pole room switches, S, control the lamps when the door 
is unlocked from the outside. 


de-energized, and switch S opens. For this reason, the 
bracket and toilet lamps cannot be lighted except when G is 
closed. The method shown in Fig. 448 will usually be more 



A--, 




3L-Fron+ Elevation 


fBo/t...*# 

Position With I 
Door Open - ■ , 

\ Door Closed 
. * , s—■ 

Hi-Side Elevation 


Position W/th 

Door C 
■'s-— - 


Fig. 452A. —Method of installing a door-bolt switch which is to be operated by a 
sliding door. (Lamps within the storeroom are lighted when the roller runs off of the 
angle iron as the door is opened. The lamps will be extinguished when the door is 
closed, even though it is not closed tightly. In some construction it may be necessary 
to provide a channel or groove in the wall for the angle iron.) 


economical from a current-saving standpoint than that shown 
in Fig. 447 or 449. 











































































330 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


Note. —A Door-bolt Switch Which Is Directly Operated By The 
Lock Bolt is shown in Fig. 451. This mechanism consists of a single¬ 
pole switch, the construction of which is similar to the door switch 
described in Sec. 95. When the door is locked from the outside, the lock 
bolt, L, (Fig. 451) strikes the switch button, B, and opens the switch. 
When the door is unlocked from the outside the switch is closed by a spring 
(Sec. 95). This door-bolt switch is connected into one side of the line as 
shown in Fig. 452. One or more single-pole room switches ( S , Fig. 452) 
control the lamps within the room when the door is unlocked from the 
outside. A method of installing such a switch for a sliding door is 
illustrated in Fig. 452A. The function of the directly operated door- 
bolt switch is the same as that of the solenoid door-bolt switch (Sec. 353). 

355. A Time Switch is a switch which is so operated by a 
clock mechanism that the switch will be automatically opened 



Fig. 453.—An improvised alarm-clock time switch. This arrangement would prob¬ 
ably not be approved by an insurance inspection bureau. (The clock is anchored to 
the shelf by notched blocks, G. A string S, is so wound around the alarm-winding 
stem C, that when the alarm goes off the string will be pulled. Pulling the string releases 
weight, B, by means of lever, L, and hinged shelf, M. The weight in falling pulls switch 
handle, H, by means of cord, R. The clip, D, is used in taking up the slack in the string.) 

or closed by the clock at a predetermined time. A simple 
time switch may be constructed by rigging an ordinary knife 
switch to an alarm clock (Fig. 453), so that when the alarm 
mechanism is tripped the switch will be operated. However, 
the commercial time switches usually comprise a high-grade 
clock mechanism, a mechanical switch propelling device, and 
a switch, all of which are compacted into a small metallic 
protecting case. The types of switches which are usually 
employed in connection with time-switch mechanisms of the 









































































Sec. 356] 


REMOTE-CONTROLLED CIRCUITS 


331 


different makes are shown in Table 369. The clock-work 
spring and the propelling-mechanism spring have to be wound 
by hand, except where an electric winding device is provided 
as in Fig. 465. Rewinding is usually required every 8 days. 
Various commercial time-switch mechanisms are described 
in the following sections. 

356. A Time Switch Can Generally Be Economically Used 
To Control A Circuit Which It Is Desirable To Open Or Close 
At Definite Times, and where there is no reliable person 
present at those times to do this work. Specific examples of 
time-switch applications are outlined hereinafter. 



Door 



Gear And 
Spring To 
Operate 
Propelling 
-Mechanism 


ol/Varmingo 
PI Coi/.w: r 


c 


K -Q 


Warming Coif Switch--' 



Fig. 454.—Double-pole, single-throw Fro. 455.—Clock and associated parts 
Anderson time switch. (Type F. Albert of an Anderson time switch showing Sun- 
tfc J. M. Anderson Mfg. Co.) day shut-off dial. 


357. The Anderson Time Switch (Fig. 454) consists of three 
principal units: (1) The clock and its associated parts , Fig. 455, 
which trip the propelling mechanism. (2) The propelling 
mechanism, Fig. 456, which operates the switch. (3) The 








































































































































































































































332 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


switch , Fig. 457, which opens and closes the circuit. The 
operation of each of these units is explained below. 



Fig. 456.—Propelling mechanism of an Anderson time switch. (Switch in open 

position.) 


Explanation. —The 24-hr. dial ( D , Fig. 455) which is geared to and 
rotated by the clockwork mechanism, makes one complete revolution 



I-Open Position HCIosed Position 


Fig. 457.—Double-pole, single-throw switch mechanism of an Anderson time switch. 


every 24 hr. The cams (E, Fig. 450) are in the rear of D and are 
carried on a shaft through the center of D. Thus, the cams E rotate 











































































































































































































































































































































Sec. 357 ] 


REMOTE-CONTROLLED CIRCUITS 


333 


with D. The relative position of these cams is changed by loosening the 
knurled nut ( N , Fig. 455) and setting the hands of the 24-hr. dial with 
the fingers. Setting these hands according to the figures on D (Fig. 455) 
determines the time at which the switch will be operated. 

The operation of the switch is as follows: Consider one of the cams 
(E, Fig. 456), which is rotated by the clock mechanism in the direction 
indicated by the arrow. When the incline of E, (Fig. 458) comes in 
contact with the projecting lug, C, E will—as it continues to rotate— 
exert a pressure on C which will cause the escapement mechanism, M, to 
tilt upward about the pivot, P, until the projection A rises high enough to 



Fig. 458.—Escapement mechanism of 
an Anderson time switch being tilted up 
by the clock-actuated cam, E. 



Fig. 459.—Propelling mechanism of an 
Anderson time switch after having made 
a portion of the one half revolution re¬ 
quired for one operation of the switch. 


allow the point of arm B to pass under it. This movement, which has 
tilted A upward, has, at the same time, tilted F downward. Therefore, 
when the upper end of arm B, which is moved in the direction of the 
arrow by the spring of the propelling mechanism, is released from A, 
it will only rotate until it strikes F, as shown in Fig. 459. Shortly 
afterward, the point of cam E passes by the knife-edge of projection C, 
thus allowing the spiral spring, S, to pull M back into its original position. 
This disengages B and F, and the operating spring of the propelling 
mechanism causes B to rotate. Rotation of B is stopped after one half 
revolution—by the other end of B striking against A as shown in Fig. 
460. This one-half revolution of B and the crank disc, H, carries the 
crank-pin, K , to a position (Fig. 460), which is diametrically opposite to 
that which is shown in Fig. 456. This lowers the connecting rod, R, and 









































































































































































































































































































































































































































334 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


closes the switch as shown in Fig. 457-77. When the next cam strikes 
C, (Fig. 460) the cycle which is described above is repeated, and R is 
raised into the position shown in Figs. 456 and 457-7. The switch is then 
open. The manner in which the switch is opened and closed through 
the toggle-link mechanism may be understood from a consideration of 
Fig. 457. 



Fig. 460. —Propelling mechanism of 
an Anderson time switch. (Switch in 
closed position.) 



Fig. 461. —Paragon time switch. ( Para¬ 
gon Electric Co.) 


358. The Paragon Time Switch (Fig. 461) consists of three 
principal parts: (1) The clock. (2) The propelling mechanism. 
(3) The switch. The type of clock shown has four hands on 
the 24-hr. dial. This permits of four operations each 24 hr. 
That is, the switch may be opened twice and closed twice 
during this period. The maximum capacity of the snap 
switch, S, is 30 amp. If a current larger than 30 amp. is to 
be controlled by this instrument, a remote-controlled switch 
is used, and S is connected through three No. 14 wires to the 
opening and closing coils of the remote-controlled switch. 

359. In The Mercury Time Switch (Fig. 462), the principal 
parts of each pole of the double-pole-switch mechanism are a 
pivoted switch blade (G, Fig. 463) and a mercury-cup, D, 
which is filled with mercury. When the switch is closed 
(Fig. 463-7), the current-path is that which is indicated by the 




















































































































































































































































































Sec. 359 ] REMOTE-CONTROLLED CIRCUITS 335 

arrows. The switch is held in the closed position by the 
spiral spring, S. If the switch handle (7/ Fig. 463-7) is 
pushed to the right, the spiral spring, S, opens the switch by 



Fig. 462.— Mercury time swatch. ( Mercury Time Switch Co.) 


raising the blade out of the mercury (Fig. 463-/7) with almost 
a snap action. If now H is pushed to the left, the switch 
is closed. In the time switch (Fig. 462), H is pushed to the 
right by a trigger arm A and to the left by another trigger arm, 




Trigger Arm - 

A 

Spiral Spring-., 
Mercury- 


y Wooden Switch Hanaie 


B 


j, ■ -Trigger Arm 

• Switch Blade 

Binding- 


Mercury 


"'Copper Strips 


Fig. 463.—Illustrating construction of the switch employed in the Mercury time switch. 


B. These trigger arms are actuated by the clock mechanism. 
The time at which it is,desired that the switch be opened may 
be set by the “off ” dial, L, and the time at which it is desired 































































































































































336 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


that the switch be closed may be set by the “on" dial, M. 
When the time arrives at which the “off” dial, L, has been set, 
the trigger arm, A, flips to the right, thus kicking the switch 
open. When the time arrives at which the “on” dial, M, 
lias been set, trigger arm B flips to the left, thus closing the 
switch. The apparatus is so constructed that each of the 
operations (one opening and one closing) described above may 
be made to occur every 24 hr. 

360. Various Devices Which Are Intended To Decrease The 
Personal Supervision Of Time Switches have been developed 
by certain manufacturers. The functions of the principal 
devices of this sort are described in the paragraphs below. 

361 . A Time Switch May Be So Made That Four Daily Opera¬ 
tions Will Occur (Sec. 358). That is, during each 24 hr., it will, say 

close the switch, then open it, then 
close it again, and then open it again. 
Time switches are also made so that 
three daily operations will occur. The 
Paragon switch (Fig. 461) will operate 
4 times daily. The Anderson Com¬ 
pany makes switches which will oper¬ 
ate respectivel}'' 2, 3 or 4 times daily. 
The Mercury switch operates 2 times 
daily. 

362 . The So-called “Sunday” 
Shut-off Device (Figs. 455 and 464) 
operates to shut off the operation of 
the switch for a period of one 24-hr. 
day in each 7 days. In those locali¬ 
ties where it is not deemed necessary 
to have the show-window or similar 
lamps lighted on Sunday night, a 
switch which is equipped with a Sun¬ 
day shut-off device may be used. 
Then the lamps will be lighted and 
extinguished each weekday at the time 
set on the dial and on Sunday they do 
not light at all. 

363 . The So-called “Saturday 
Night Overtime” Device {Albert 

& J. M. Anderson Mfg. Co.) operates to cause the time switch to auto¬ 
matically interrupt the current later, say 2 hr. later, on any one night 
out of seven than the time at which it operates on the other nights. 
That is, the switch may be set to extinguish the lights, say, at 11:00 p.m. 



Fig. 464.—Showing the Sunday cut¬ 
out mechanism on an Anderson time 
swatch. (Every seven days a cam, E, 
so operates the latch, L, that the arm 
is prevented from rotating for a period 
of 24 hr.) 


























































































































































































Sec. 364] 


REMOTE-CONTROLLED CIRCUITS 


337 


on e\ery night except Saturday, on which night it does not extinguish 
them until 1.00 a.m. Sunday. Such a device is especially desirable in 
connection with a time switch for controlling the lights in a show window 
in the business section of a city. 

364 . A Warming Coil On A Time Switch ( Anderson and Paragon) 
is used to warm the clock when it is exposed to extremely low tempera¬ 
tures. If the temperature of the clock drops to about 0° F., the oil will 
thicken and cause the clock either to run slower or to stop altogether. 
The warming coil is intended to prevent this. The warming-coil circuit 
on some clocks is provided with a thermostat so that the coil is auto¬ 
matically cut out of circuit in warm weather and cut in again in cold 
weather. The warming coil on other 
clocks (IF, Fig. 454) is provided with 
a switch whereby the coil is manually 
connected and disconnected. 

365 . By Equipping A Time Clock 
With A Switch-lock-out Device, 

(P aragon switch ) the switch-propelling 
mechanism may be prevented from 
operating while the clock continues 
to mark time. This lock-out device 
is usually manually operated. If it is 
desired to discontinue the switch 
operation for one or more days, the 
switch is locked by this device. 

Then when the switch is unlocked, 
the regular cycle of switch operation 
will be resumed. 

366 . An Electrically-wound Time Switch (Fig. 465) is one wherein 
the propelling-mechanism spring and the clock mainspring are wound 
automatically by an electric current. Such an appliance is especially 
advantageous for a time switch which is to be installed in an isolated 
location, such as an outlying series-arc-lamp sub-station, or on the 
framework of an electric sign which is on the top of a high building. 
The only attention, so the manufacturers claim, that will be required 
by a time switch which is so equipped is to change the setting to cor¬ 
respond with the change of seasons and to oil it about twice a year. 

367 . A Season Changing Device On A Time Switch causes the 
time at which the switch opens and closes to vary according to the time 
at which the sun rises and sets. One manufacturer (A. & J. M. Anderson 
Mfg. Co.) of such a device states that when adjustments are made for 
the latitude where the time switch is to be used, the instrument will 
follow the sunrise and sunset with a maximum error of about 15 min. 
from sunrise on Aug. 15 and a similar error of 15 min. from sunset 
on May 15, but will be practically correct on Dec. 15 and June 15. 

That is, assume that the time switch is set at Boston, Mass, on June 15, 
so that the lamps will be extinguished at 3:05 a.m. and lighted at 8:25 p.m. 

22 



Fig. 465.—Wiring diagram of an elec¬ 
trically-wound, high-voltage, oil-break 
time switch. ( Type T, Albert & J. M. 
Anderson Mfg. Co.) 









338 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


(These times are, respectively, about 1 hr. before sunrise and 1 hr. after 
sunset at Boston, Mass, on June 15.) Then, without further attention 
to the setting, the instrument will, on Aug. 15, extinguish the lamps at 
about 3:30 a.m., which is about 1 hr. and 5 min. before sunrise. On the 
'same date the lamps will be lighted at 7:45 p.m., which is about 1 hr. after 
sunset. On Dec. 15, it will extinguish the lamps at 6:05 a.m. and light 
them at 5:10 p.m., which times are, respectively, again 1 hr. before sun¬ 
rise and 1 hr. after sunset, just as the settings were made on June 15. 

368 . From the explanations in the preceding notes it is evident that 
certain manufacturers’ time switches may be so equipped that they 
will operate every day in the week, do overtime on Saturday night, rest 
all day Sunday, warm itself when the weather gets cold, wind itself, and 
follow the seasonal changes in the time at which the sun rises and sets. 

369. Table Showing Classification Of Time Switches As 
Regularly Manufactured By The Anderson Company Accord¬ 
ing To The Type Of Switch. 


Type of break 

Type of mechanism 

Operation 

Air break 

Snap switch (Fig. 466) 

. 

Electrolier 

Single-pole, single-throw 
Double-pole, single-thrbw 
Three-pole, single-throw 

Laminated copper brush 
(Fig. 454) 

Single-pole, single-throw 
Double-pole, single-throw 
Double-pole, double-throw 
Three-pole, single-throw 

Oil break 

Laminated copper brush 
(Fig. 469) 

Double-pole, single-throw 
Three-pole, single-throw 


370. The Applications Of The Switches Of The Different 
Types Which Are Used In Time Switches are, in general, as 
noted below. 


Note.—Time Switches Which Are Equipped With A Snap Switch 
are used to control small loads not exceeding 30 amp. at 250 volts, such as 
small lighting loads and remote-controlled switches. The remote- 
controlled switch may in turn control a load of any reasonable magni¬ 
tude. Air-break time switches which have laminated copper brushes 
are used to control loads from 10 to 250 amp. at not over 250 volts. 
Oil-break time switches are used for loads up to 50 amp. at from 500 
to 6,600 volts. 























Sec 371] 


REMOTE-CONTROLLED CIRCUITS 


339 


371 . The Cost Of Time Switches varies from about $35.00 up to 
$450.00, depending upon the type, capacity, and (Sec. 360) appliances. 
For estimating purposes the following costs may be assumed: A 
30-amp. switch costs about $75.00; a 60-amp. switch about $100.00; a 
100-amp. switch about $300.00; and a 200-amp. switch about $400.00. 
The various special appliances which are listed in Secs. 362 to 368 may 
cost from $5.00 to $50.00 extra. 

372. The Circuit-connections For A Time Switch will 
depend upon the type of the switch which is used. The circuit 
diagrams given in Divs. 4 and 7 for single-pole, multi-pole or 
electrolier switch circuits may be followed for connecting time 
switches of the respective types. 

Note.—The Electrolier Switches Which Are Designed For Use 
In Connection With Time Switches are usually two-circuit, three 
position (Div. 7) electrolier switches. Such a switch usually requires 
that the time switch mechanism be provided for three operations daily. 
That is, one time switch operation per day must be provided for each 
electrolier switch position. For example see Sec. 375. 

373. The Kinds Of Lighting-circuit Installations Which 
Time Switches Are Frequently Used To Control are: (1) Signs. 
(2) Show windows. (3) Hall-ways of apartment houses. (4) 
Poultry houses. (5) Electric railway waiting stations. (6) 
Two-rate meter service installations. (7) Street lamps. Time 
switches are also frequently used to control the length of 
time which storage batteries are on charge, to control motors 
for ventilation and refrigeration, and the like. Since storage 
battery and motor applications are not within the scope of this 
book, only those listed above from (1) to (7) inclusive, will be 
described in the following sections. 

374. Time Switches May Be Used To Control The Lighting 
Of Outdoor Electric Signs, both of the flasher and of the 
constantly-lighted types. Where a time switch is used to 

„ control a flasher sign, it may be so connected that both the 
lamps and the motor which drives the flasher are controlled 
by the same switch. Where several bill-boards which are 
owned by the same company are grouped close together, one 
time switch may be used to control the lighting of the entire 
group. Such installations, instead of requiring an attendant 
to visit them twice daily to turn the lamps on and off, will 
only require an occasional inspection of the lamps and time 


340 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


switch. If the time switch mechanism is not electrically 
wound, it will have to be periodically wound by hand, ordi¬ 
narily once each week. 

375. Time Switches May Be Advantageously Used To Con¬ 
trol The Lamps In Show-windows which are not under the 

care of a night-watchman. Even 
where there is a community 
night-watchman whose duty it 
is to turn the window lamps on 
and off at given hours, a time 
switch may pay for itself in a 
few years by the current saved 
and by eliminating the night- 
watchman’s fee. Where it is 
desired that the illumination of 
a brightly lighted window be 
decreased during the night, the 
lamps may be connected to two 
circuits. Then by controlling 
these two circuits with a two- 
circuit, three-position electrolier 
time switch which operates three 
times daily, all of the lamps may 
be automatically turned on at 
dark. Then, later in the even¬ 
ing when traffic has decreased, 
a part of the lamps may be ex¬ 
tinguished and a part left 

burning. Finally, just before 

Fig. 406. Anderson^ Type p time daybreak, all of the lights may 

be extinguished. The electrolier 
switch for such service should provide a “1 & 2—1—Off” 
control sequence. Figs. 461 and 466 show time switch 
mechanisms which operate electrolier switches. 

376. Time Switches May Be Used To Control The Hall¬ 
way Lights Of Apartment Houses where it is desired to 
extinguish all of the hall lights at a certain hour. Or they 
may be employed where it is desired that only a part of 
the hall lamps be extinguished at a certain hour of the night 


































































Sec. 377] 


REMOTE-CONTROLLED CIRCUITS 


341 


and the remainder be left burning until morning. For this 
latter control the lamps are connected to two different circuits. 
Then the two circuits are controlled by a two-circuit three- 
position electrolier time switch which operates three times 
daily (Sec. 375) 

Note.—Time Switches Are Sometimes Used To Control The 
Lamps In Poultry Houses, thereby increasing the apparent daylight 
period, and providing a longer working day for the poultry. This is 
believed by some poultrymen to increase egg production. 

Note.—The Lamps In Railway Waiting Stations May Be Con¬ 
trolled By Time Switches so that, at stations where there is no agent 
or attendant, the lamps will not be left burning during the day time or 
during the night hours when there are no trains. The type, capacity and 
connections for the time switch controlling such lamps will be essentially 
the same as for a manually operated switch for the same service. 



Peak- 

_ i Load- 

•: i) Period- 
y Meter 


-Qr 


377. Two-rate Meter Service May Be Controlled By A 
Double-pole Double-throw Time Switch (Fig. 467) which has 
no off position. Central sta¬ 
tion companies will sometimes 
sell electrical energy which is 
used during the light-load period 
at a lower rate than that which 
used during the peak-load 


Light- * 
Load- 
Period 
Meter 



IS 








Lamps-'' 






a- 




Line To 
Service Switch 
>-And Fuses 


Double-Pole, Double- f 
Throw Time Switch} 

Which Has No 
Open Position-'' 

Fig. 467.—Diagram of connections 
for two-rate meter service controlled by 
a time switch. 


period. In such cases, a time 
switch may be used to transfer 
the load from one meter to the 
other at specified times. 

378. The Extinguishing And 
Lighting Of Series Arc And Incandescent Street Lamps May 
Be Controlled By Time Switches. Series street lamps, 
whether arc or incandescent, may be served from: (1) A 
constant-current transformer. (2) A constant-potential trans¬ 
former. (3) A constant-potential auto-transformer. (4) Direct 
from a constant-potential feeder. Various methods which are 
employed and the types of time switches used for controlling 
each are described in the following sections. 

379. A Time Switch Of A Special Type Is Generally 
Required For The Control Of A Series Lamp Circuit Which Is 
Fed By A Constant-current Transformer. If the coils of a 






















LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


342 


constant-current transformer are close together when the lamp 
load is switched into the circuit, considerable damage to the 
lamps may result. Consequently, it is necessary that 


2200-VoIt A.C. Line 


Single- Pole 
Single- Throw 
Switches .... 


Single-Pole 
Single Throw 
Switch 



Constant 
Current 
Transformer 

Fig. 468. — Wiring diagram of a time switch which automatically separates the coils 
of a constant-current transformer before the series lamps are connected into the circuit, 
(Type M; A. & J. M. Anderson Mfg. Co.) 

the coils be separated before the lamp load is thrown on the 
transformer. A time switch which automatically effects 
this coil-separation before the lamps are lighted, employs 

three single-pole switches (A, B 
and C, Fig. 468); the operation is 
as follows: 

Explanation. —Two of the switches 
(A and B, 468) are connected into the 
primary of the transformer. These 
two switches (A and B ) are simul¬ 
taneously opened and closed by the 
clock mechanism. The third switch, 
C, is connected across the terminals 
of the secondary circuit. Switch C 
closes simultaneously with switches A 
and B and acts as a short circuit on 
the secondary of the transformer. 
This separates the transformer pri¬ 
mary and secondary coils a sufficient 
distance to prevent an excessive cur¬ 
rent from flowing in the secondary 
circuit. However, switch C remains 
closed only until the short-circuited current in the secondary has sepa¬ 
rated the constant-current-transformer coils, as just described. Then, 
C, is automatically opened by the clock mechanism and the series lamps 
are lighted. 

Note.— A Constant-current Transformer Circuit May Be 
Controlled By An Ordinary High-potential, Oil-break, Double¬ 
pole Time Switch (Fig. 469) connected into the primary as indicated in 



Fig. 469.—Double-pole, single-throw 
oil-break time switch with oil tank 
removed. (A. <fe J. M. Anderson Mfg. 
Co.) 





































































Sec. 380] 


REM0 TE-CON TROLLED Cl RC UITS 


343 


Fig. 470. With this arrangement, wooden blocks, W, are placed between 
the transformer coils. The thickness of the blocks should be such that 
when the lamps are off the secondary coil will drop to a position which is 
just a little below its full-load position. 



Fig. 470.—Wooden blocks used to keep the primary and secondary coils of a constant- 
current transformer separated, so the series lamps may not be damaged when the time 
switch closes. 


Auto -Transformer 


380. For Controlling A Series-lamp Circuit Which Is 
Served By A Constant-potential Or Auto-transformer, A 
Time Switch May Be Used as indicated in Fig. 471. The 
high-potential, oil-break, double¬ 
pole time switch is merely con¬ 
nected into the primary leads 
which serve the transformer. 

381. A Time Switch Designed 
For Controlling Individual 
Series Lamps, as illustrated in 
Fig. 472, is mounted inside of 
the pole fixture. This switch 
will not turn the lamp on. This must be done by a patrol¬ 
man. However, the switch will turn the lamp off after it has 
burned the number of hours which is indicated by the number 



■- 0r _ • ' Double-Pole , Oil-break 

Pnmary Jjme Slr/yW) 


Fig. 471.—Time switch for controll¬ 
ing a series-lamp circuit which is served 
by an auto-transformer. 















































































344 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


on the dial, D, to which the indicator, /, points. When set 
as shown in the illustration, the switch will turn the lamp 
off 10 hr. after the patrolman turns it on. 



Fig. 472.—Time switch for controlling individual series lamps. (Type R; A. & J. M. 

Anderson Mfg. Co.) 

382. In Installing Time Switches, whether indoors or out¬ 
doors, it should be remembered that satisfactory operation of 
the switch depends upon the proper functioning of the clock¬ 
work mechanism. Therefore, the instrument should be 
protected from moisture and dust. The cases of some time 
switches are made practically dust and moisture proof, 
whereas some are not so made. Oil-break time switches which 
are installed on poles or in other exposed places should be 
enclosed in a wooden housing to provide additional protection 
against the elements. See Sec. 364 which relates to the electric 
warming of time switch mechanisms. 

383. The Code Requirements For Switches Of Time 
Switches are the same as those for a manually operated switch 
(Div. 3). Code Rule 19 d states that: Time switches must he 
of approved design and enclosed in approved cabinets. Con¬ 
sequently, all approved time switches are enclosed. 


































































Sec. 383] 


REMOTE-CONTROLLED CIRCUITS 


345 


Note. The Case Of A High-potential Oil-break Time Switch 
Should Be Grounded as indicated in Figs. 465 and 469. This is for 
protection of a workman against a possible insulation breakdown. 

QUESTIONS ON DIVISION 8 

1. What is a remote-controlled switch? Ry what other names is it frequently 

called? Draw a simple sketch of, and explain the operation of a remote-controlled 
switch. 

2 . Strictly speaking, in what two ways may a remote-controlled switch be con- 
tioiled? How are switches which are used to control high-voltage circuits sometimes 
controlled? 

3 . For what purposes may remote-controlled switches be used? Give specific 
examples wherein remote controlled switches are used for lighting service. 

4 . How may remote-controlled switches be classified according to operation? Define 
each classification. 

5. Why is an electrically-held-closed remote-controlled switch better adapted for 
the control of motors than a mechanically-held-closed switch? 

6. Why is a mechanically-held-closed remote-controlled switch better adapted for 
the control of lamps than one which is held closed electrically? 

7 . Name, define, and make a sketch of each of the principal types of remote-con¬ 
trolled switches. 

8 . Explain with a sketch, the operation of a straight-line-movement, mechanically- 
held-closed remote-controlled switch. 

9. Explain by sketch the operation of a mechanically-held-closed switch of the 
clapper type. 

10 . For what service is the Major remote-controlled switch especially suited? Why? 
Make a sketch of the Major switch to explain its operation. 

11 . Explain, with sketch, the operation of an electrically-held-closed remote-controlled 
switch of the clapper type. By what other names is this type of switch sometimes 
called? 

12. Explain by sketch the operation of an electrically-held-closed, straight-line- 
movement, remote-controlled switch. 

13 . Illustrate with a sketch the two separate circuits of a remote-controlled switch. 

14 . Define the control circuit and the load circuit of a remote-controlled switch. 
What constitutes these circuits? Upon what do the control-circuit connections depend? 

15 . What types of switches are usually employed to control an electrically-held-closed 
remote-controlled switch? 

16 . What type of switch is generally used to control a mechanically-held-closed 
switch? 

17 . Explain the type of momentary-contact switch which is generally used to control 
a remote-controlled switch of the mechanically-held-closed type. 

18 . Draw a sketch of the control-circuit diagram to provide single-location control 
of the following makes of switches: (a) Hart, Type F. (b) Cutler-Hammer, (c) Major, 
(d) Sundh. (e) Automatic. 

19 . Draw a sketch of the control-circuit diagram to provide three-location control of 
those makes of switches which are listed in Question 18. 

20. Explain by sketch how a wire-saving may be made in a remote-control installation 
when the momentary-contact switches are mounted in gang and the remote-controlled 
switches are mounted on one panel board. If an installation is made according to 
this method, how much wire will be saved if there are 9 remote-controlled switches 
which are located 125 ft. from the momentary contact switches? 

21 . Draw a sketch of the control-circuit diagram to provide single-location control of 
an electrically-held-closed switch. 

22 . Draw a sketch of the control-circuit diagram to provide three-location control 
of an electrically-held-closed switch. 

23 . Draw a sketch of the control circuit diagram to provide three-location control 
of an electrically-held-closed switch. 


346 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 8 


24 . Draw a sketch of the control-circuit diagram of a Hart Type A remote-controlled 
switch, wherein single-location control is provided by a single-pole controlling switch. 
Make a sketch of same, using a two-circuit momentary-contact switch. Describe the 
type of momentary-contact switch which is required for this service. Explain the 
difference in the low-voltage protection which is provided by each method. 

25 . Show by sketch how two or more remote-controlled switches may be controlled 
by one momentary-contact switch. In a remote-controlled switch wherein the operating 
current is broken by the switch mechanism, what determines the number of remote- 
controlled switches which may be controlled by one momentary-contact switch? What 
determines the number of remote-controlled switches which may be controlled by one 
momentary-contact switch if the operating current is broken by the momentary-contact 
switch? 

26 . Make a sketch of the connections for two remote-controlled switches which are 
so connected that double-throw switch operation is provided by one momentary-contact 
switch.- 

27 . Make a sketch of the diagram of connections of two remote-controlled switches 
so interconnected by a relay that upon failure of the regular service, the load will be 
automatically transferred to the emergency service. Explain its operation. 

28 . Show by sketch how the installation in Question 27 may be remotely controlled. 

29 . What three sources of electrical energy may be utilized for the control of remote- 
controlled switches? 

30 . Name seven different contacting devices whereby a remote-controlled switch may 
be controlled. 

31 . Describe the type of remote-controlled switch which should be used when a 
device other than a momentary-contact switch is used to control it. 

32 . Draw a sketch of the control circuit of a remote-controlled switch to show how it 
should be fused to comply strictly with Code requirements. 

33 . Make a sketch of the control circuit of a remote-controlled switch to show how 
it is generally fused when used in connection with a system which has a grounded- 
neutral. Explain why such a method of fusing may be considered safe. 

34 . Make a sketch to show how the control circuit should be fused when the remote- 
controlled switch is used to control a circuit which has no grounded-neutral, such as a 
three-phase, three-wire circuit. 

35 . How should a remote-controlled-switch circuit be fused? 

36 . What are the factors which determine whether a remote-control or a direct-control 
lighting system should be used? What are the conditions which determine these 
factors? 

37 . What costs are included in the annual fixed costs of an installation? What costs 
are included in the annual operating costs? 

38 . Explain the general method which should be followed in selecting which system 
direct-control or remote-control should be used. 

39 . Make dimensioned sketches (select your own dimensions) to show how a saving 
may be effected by a remote-control installation over a direct-control installation where 
the load center, the service entrance and the control location are separated by a con¬ 
siderable distance. How many feet of wire do you save? 

40 . Make a sketch of the distribution panel of a remote-controlled switch designed for 
the control several 660-watt branch circuits. 

41 . Make two sketches of multi-location-control installations of remote-controlled 
switches, and give two specific examples of their application. 

42 . Make a sketch of connections for remotely controlling arc lamps in a moving- 
picture studio. Explain its operation with an actual example. 

43 . For what types of buildings are remote-controlled switches not usually economical 
when used as a master switch? Explain by sketch, showing wiring diagram for both the 
remote- and the direct-control of the master circuit in such a building. 

44 . Make a diagram of connections of a remote-controlled master circuit, wherein the 
location controls of the various lamp-groups are provided by single-pole switches. 

45 . What is a door switch? What two types of door switches are frequently used? 
For what purpose is each type used? 


Sec. 383] 


REMOTE-CONTROLLED CIRCUITS 


347 


46 . For what purpose is a solenoid door-bolt switch used? Make a diagram of the 
connections and explain the operation of a solenoid door-bolt switch. Make a diagram 
of connections for a solenoid door-bolt switch installation wherein all of the lamps in the 
room may be controlled by a double-pole room switch, so that no current will flow 
through the solenoid except when this double-pole switch is closed. 

47 . What is a time switch? 

48 . Under what conditions are time switches generally desirable? 

49 . Explain the operation of the Anderson time switch; of the Paragon; of the Mercury. 

50 . Explain the function of each of the following time-switch appliances: (a) Sunday 
shut-off device, (b) Saturday night overtime device, (c) Warming coil. ( d) Switch- 
lock-out device, (e) Electric winding apparatus. (/) Season changing device. 

51 . Give classifications of time switches according to: (a) Type of break. ( b) Type 
of mechanism, (c) Operation. 

52 . Give the voltage and ampere range for which time switches are suitable when 
equipped with: (a) Snap sivitch. (b) Air-break laminated-copper-brush switch, (c) 
Oil-break switch. 

53 . Name seven examples wherein time switches are frequently used to control 
lighting circuits. 

54 . Can a time switch be used for controlling a circuit other than a lighting circuit? 

55 . Explain why a time switch may be desirable for controlling electric signs. 

56 . What type of switch mechanism will frequently be found useful in connection 
with a time switch used for controlling the lamps in show-windows. 

57 . What type of switch mechanism should be used in a time switch which is to 
control a two-rate meter service? 

58 . What two kinds of transformers may be used to serve series arc or incandescent 
street-lamp circuits? 

59 . Explain the operation of one type of time switch which is especially designed for 
controlling a series street lamp circuit which is served through constant-current trans¬ 
formers. Draw a sketch of the diagram of connections. 

60 . Make a sketch of and explain how a constant-current-transformer circuit may be 
controlled by an ordinary double-pole, oil-break time switch. 

61 . Make a sketch of the diagram of connections for controlling a series lamp circuit, 
which is served by a constant-potential or auto-transformer, with a time switch. 

62 . What should be remembered in installing time switches? 

63 . Give the Code requirements relating to time switches 


DIVISION 9 


THEATRE LIGHTING CIRCUITS AND SWITCHING 

384. The Principal Requirements To Be Considered In 
Laying Out The Circuits For Theatre Lighting are: (1) 
Safety of the patrons. The emergency circuits (Secs. 399 to 
402) must be so arranged that every possible precaution 
against the disastrous result of a panic is provided. (2) The 
decorative effect. The decorative effect which is provided by 
the lamp-arrangement as made by the architect depends to a 
large extent on the lighting control. That is, unless the 
control of the house and stage lights (Secs. 413 and 414) is 
extremely flexible, those illusions which may be produced by 
lighting effects, and which are paramount to the success of 
any show house, cannot be maintained. (3) Continuity of 
service, upon which depends both the safety of the patrons and 
the decorative effect. (4) Minimum expense. By a judicious 
circuit-layout, both the installation and operating costs may 
be reduced, and yet comply with the three requirements 
mentioned above. The general principles pertaining to the 
arrangement of theatre lighting circuits which are outlined 
subsequently in this division represent the most modern ideas 
that are in accordance with the above requirements. 

385. The Circuits For A Theatre May Be Generally Classi¬ 
fied as: (1) The services, ( R, M and L, Fig. 473) which connect 
the street mains of the public service company to the theatre- 
service-entrance equipment. (2) The feeders, mains, and 
brariches (F, Fig. 473) which connect the service-entrance 
equipment to the various energy-consuming devices and 
distribution cabinets. (3) The branch circuits (Fig. 482)' 
which connect the various distribution cabinets to the lamps. 
Each of these are discussed subsequently herein. 

386. The Service Wires For A Theatre May Be Either 
Overhead Or Underground. Which type of construction is 

348 


Sec. 387J 


THEATRE CIRCUITS 


349 


used will depend upon local practice and conditions. That is, 
if the nearby street-main is overhead, the theatre service will 
be overhead, at least as far as the theatre wall. And, if the 
street main is underground, the service will generally be 
underground. However, variation from this practice is 
sometimes necessitated because of the relative location of 
the theatre, other buildings, and of the street-main. Under¬ 
ground construction is preferable from the standpoint of safety 
and maintenance cost, whereas overhead construction is 
usually less expensive insofar as first cost is concerned. 



- _ L/L/' b • General- Power Cabinet 
Jp3 R '$ \y "General-Lighting Service 

^SerWcT^ '"General-Power 5ervice 
Fig. 473.—Typical theatre-wiring layout showing services, panels, and feeders. 


387. Theatres Are Usually Provided With Three Separate 
Services (Fig. 473) as follows: (1) The general-power service, M. 
(2) The emergency service, R. (3) The general-lighting service, 
L. Where the power requirements of a theatre are small, the 
general power service may sometimes be omitted. The func¬ 
tion of each of the above-mentioned services is outlined in the 
following sections. 

Note. —A Theatre Should Have At Least Two Services. (See 
Code Rule 38a.) If there are only two services, one of these services— 
the general-lighting service, (Sec. 393)—must have sufficient current- 
carrying capacity to supply energy for the entire equipment of the theatre 
while the other service—emergency service, (Sec. 390)—must be at least 
of sufficient capacity to supply current to all emergency lights (Sec. 402). 






























































350 


[Div. 9 


LIGHTING CIRCUITS AND SWITCHES 

389. The Energy Which Is Required To Drive The Various 
Motors Is Delivered By The General-power Service (M, Fig. 

473). With the exception of the small motors which drive the 
projection machine, all motors, such as may be used to drive 
the ventilating and air-washing apparatus, organ blower, 
bilge pump, fire pump, vacuum-cleaning apparatus, motor- 
generator or converter, and the like, are usually served by the 
general-power service. The small projection-machine motors 
are driven by current from the general-lighting service (Sec. 
407). 

390. The Energy For Lighting The Emergency Lamps Is 
Delivered By The Emergency Service (R , Fig. 473). These 

emergency lamps consist of those lamps which always remain 

lighted throughout the entire 
program, such as the aisle lamps, 
exit-door lamps, a portion of the 
lamps in the foyer, lobby, stair¬ 
ways, corridors, courts, and other 
portions of the theatre to which 
the public has access. See Sec. 
402. 

391. Where Feasible, The 
Emergency Service And The 
General-lighting Service Must 
Be Connected To Different 
Street Mains, as suggested in 
Fig. 474. Where it is impracti¬ 
cal to do this, the emergency-light feeder must be connected 
to a point on the street side of the main service fuses as 
shown in Fig. 475. In some installations where only one 
street-main is available, two separate services are run to the 
street-main and preferably connected to two separate trans¬ 
formers but sometimes to the same transformer, as shown in 
Fig. 476. Then, if frequent energy-supply failures occur, it 
may be necessary to have the lighting company run another 
main up to the point where the emergency service connects 
to the transformer; whereupon, the emergency service is then 
connected to the new main and a new transformer. 


^■Lighting Company's Mam | 


3 * 

o> 


Alley-''" 


YZZZZZZZZZZZZZZ 


General- 
Lighting 
Cabinet 
Under Stage 

'^Office Building 

Emergency... 


.-=70 

_Stage 

Theater 

Auditorium 


Emergency 
Service 

? n; Lobby 


<b> 


I 

£ 




/ y//7/-// ■/////////. / > 

7777/7 //////// 


Vo 

: 


Sidewalk-'' Streel 

H.' .. v 

- T7T“ 

. .. . - ID"’ 


Fig. 474.—Where feasible, the emerg¬ 
ency service and the general-lighting 
service are connected to separate street 
mains. 






















Sec. 392 


THEATRE CIRCUITS 


351 


^ Note. Some Cities Require, In Addition To The Regular 
Emergency Service, An Auxiliary Storage-battery Energy- 
suppL'i For 1 he Emergency Circuits. The city of Cleveland requires 
this. The storage battery is only used when the regular emergency 
service fails. The storage-battery circuit and the regular emergency 
service are connected to the emergency-cabinet feeder through a double- 
throw switch. Frequently, this double-throw switch is so operated by a 



Fig. 475. —Showing method of con¬ 
necting emergency-lighting feeder to 
main service on the street-side of the 
main service switch. 



Fig. 476. —Showing emergency service 
and general lighting service connected to 
same transformer. 


relay (Sec. 335) that when the regular emergency service fails, the switch 
is automatically thrown over and connects the emergency circuit to the 
storage-battery circuit. 

392. The Reason For The Separate Emergency Service 

is to provide every reasonable assurance against failure of 
the 11 emergency ” lights, which supply sufficient illumination 
to enable patrons to see their ways out of the theatre in case 
of failure—fuse-blowout due to short-circuit or ground—of 
the general-lighting circuit. Hence, only porcelain, keyless 
sockets serving only incandescent lamps, in which No. 14 
or larger wire is carried direct to the socket, is permitted on 
these circuits. Fans cannot be served from emergency cir¬ 
cuits. The wattage of each emergency-circuit branch is limited 
to 660 watts. 

Note.—The General-lighting Circuit Is More Susceptible To 
Troubles Than Is The Emergency Circuit. This is because of the 





















































352 


LIGHTING CIRCUITS AND SWITCHES 


[Drv. 9 


fact that portable equipment, such as olivettes and bunch-lights are 
often plugged in on the general lighting circuit by means of stage pockets 
(Fig. 477). Grounds or shorts may occur in the cords which feed this 
equipment. It is a fact that all of these circuits should be properly 
protected with N.E.C. fuses. But in practice they are likely to be 
"fused” with nails, copper wire, or any other metal which the electrician 
finds handy when he is endeavoring to close a circuit quickly so that the 
performance may proceed. Furthermore, the apparatus in the projection 
booth—motion-picture machine and stereoptican arc lamps—and the 
motors which operate the projector and the rewinding machine, are all 



Fig. 477.—A two-receptacle stage pocket. (Frank Adam Electric Co.) 


served from the general-lighting circuit (see 0, Fig. 482). This equip¬ 
ment, which is used almost continually, is liable to be the source of 
troubles which will interrupt the general-lighting-circuit energy supply. 

Note.—A Combination Non-interchange able Arc-and-incandes- 
cent Stage Pocket is shown in Figs. 477 and 478. A groove ( G , Fig. 
479) is provided in the side of each plug. In the incandescent plug 
(Fig. 479-7), the groove, G, is in the lower part, and in the arc plug 
(Fig. 479-77), the groove is in the upper part. If a round-head screw, S, 
is put in the upper of the two holes of the receptacle A (Fig. 477), that 
receptacle becomes the arc receptacle. This is because, on account 
of the groove ( G , Fig. 479-77), only the arc plug can be inserted therein. 
If the screw is inserted in the lower hole, as shown at R, that receptacle, 



Sec. 393] 


THEATRE CIRCUITS 


353 


477) becomes on account of the groove, G, in the incandescent 
plug, Fig. 479-7 the incandescent receptacle. Thus, when one screw is 
put in the upper hole of one receptacle, and another screw is put in the 
lower hole of the other receptacle, the arc and incandescent plugs are 
non-interchangeable. 



Me tat Contacts 

Ejj|B 




‘ ; , - : * 

■ Groove Q-^ 



I-lncandescen-t Plug 

Composition, 



' Groove £ 


m umm 


I 

! 



I-Arc Plug 


Fig. 479.—Arc and incandescent plugs 
for a combination stage pocket. 


393. The Energy Which Is Delivered By The General¬ 
lighting Service (L, Fig. 473) is used to light all lamps in the 
theatre except (Sec. 390) the emergency and exit-sign lamps. 
That is, the general-lighting service carries the current for 
the lamps which light the: (1) Stage . (2) Auditorium. (3) 

Offices. (4) Signs. (5) Toilets. (6) Dressing rooms. (7) 
Rest rooms. (8) General illumination of foyer and lobby. 
The distribution centers which are fed by feeders from the 
general-lighting cabinet are given in Sec. 404. 


Note.—The Voltage And The Kind Of Current-supply For 
Theatres will usually be that which is the more-readily available. 
However, the general practice is to use 110-220 volt, three-wire, single¬ 
phase supply for the emergency- and the general-lighting circuits. The 
current for the power circuit is usually supplied at 220 volts, three phase. 

394. Each Service Must Be Provided With A Separate 
Service Switch, Service Fuses And Meter. The service 
switch and service fuses must, in general, be so wired and 

23 




































































































































354 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


located as to comply with the Code requirements as outlined 
in Div. 3 for service entrances. The service switches and the 
main distribution panels may, if they are located in a separate 
room which is accessible only to properly-informed persons, 
be mounted on an open switchboard. However, if they are not 
so located, they must be enclosed in suitable metal cabinets. 

Note.—The Type Of Service Fuses which are generally used for 
capacities of 800 amp. and below is the N.E.C. Standard (cartridge, or 
enclosed). For capacities of 1,000 amp. and above, open-link fuses or 
circuit-breakers are nearly always used. The cities of Chicago and 
Cleveland compel the use of circuit-breakers for capacities greater than 
1,000 amp. 

395. The Most Desirable Location For The Service Boards 

service switch, service cutout, and meter—for each of the 
services (Sec. 387) is usually in the basement under the stage 


■H 

U 

w 

+- 

\n 



nswr? (t.s;.".’.-. ,i 


Auditorium 

General- 

Lighting Cabinet- 

Emergency- 
Service Board- - ■'/ 


o 




31 

OP 


i 


General-Po wer Cabinet ■ • 


Fig. 480.—Service boards in stage- 
basement. 


rTZTV.V,. 


I 

ir 

<5 

+- .£ iS? 
n 2 ^ 




r 

<ia,V 


T"~~. .\ 

a Auditorium v 

Generai Lighting 
Service Board 

Emergency 
-Service Board 


[-Power Service 
Board 


Street Mains 


to 

s 

+• 

vn 


Fig. 481.—Service boards in lobby- 
basement. 


(Fig. 530), as suggested in Figs. 473 and 480. The principal 
reasons lor this are: (1) The street mains are usually in the 
back alley and are nearer to the stage-basement than to any other 
pent of the theatre. (2) There is usually more available space 
in the stage-basement. (3) They are readily accessible to the 
electrician. During the performance, the electrician is usually 
on the stage. Consequently, if trouble at the service boards 
develops, it may, if they are under the stage, be more quickly 

corrected by him than if the boards were located at the front 
of the building. 

Note.—It Is Sometimes Impractical To Locate The Service 
Boards In The Stage-basement. Inspection departments usually 
require that the service-entrance equipment be located as near as possible 
to the point (not over 3 ft. distant, unless lead-covered cable in iron con- 



































Sec. 396] 


THEATRE CIRCUITS 


355 


duit is used) where the service enters the building. Therefore, if the 
public service company’s mains are in the street in front of the theatre, 
it may, since in such cases the feeders are usually run underground, 
be more desirable to locate the service boards in the basement under the 
lobby as shown in Fig. 481. Whether the service boards are located 
under the lobby or under the stage will not materially affect the general 

locations (see following sections) of the various distribution cabinets. 

• 

396. The Diagrammatic Plan For A Theatre Circuit Layout 

which is illustrated in Fig. 482, typifies that which is used in 


Electric Company .... 
Street-Mains v>'—^ 

'•••> 


STREET 


I General-Power Service N General • L igh ting Service 


Service 
Switch 

Service 
Cutout--■ 


branches 


«! A, 


'' y 

L- l_ L- 

o o<u 

in 

§5c 

>o 

O 1 

I 

-Q 


u_ 




% 


General- general- 
Power Lighten a 
Cqbinet Cabinet 
k* 

Meter Feeders 




vP 

L. 

O 

4 - 

O 

21 

CP 

D 

V- 

sz 


■Front-Door marts 
Cabinet—■> 
Tunnel < 
Toilets^ , 
Offices^VV 



■szzazmzzzBZBBzi. 


.Service 

Switch 

■■Service 
Cutout 

'-Meter 


Rest 

Rooms 


Emergency 
Service 
Board .> 

Meter--''' 

Sign Branch-. 
Cabinet Cufouf 
5witch-' 

f}5ign 
Branches 


B 


Emergency 
■Service 


< 


Z 


Service 
Switch 14 

■■Service 
Cutout 


Branches To 
Emergency 
Lights 




4- 


Branches 

Booth 
Lamps4 
Picture- -4 

Machine Motor- 
Mlotors Generator 
Or Converter 


■Sub feeder 


■-Emergenty 

Cabinet 


' > Pa'np\ > \ Dimmer . 

p or \ b ranchesy...rr::: g 3 cyfe < °~ 
Converter 1 




4- 


Picture-Booth Cabinet 

For Lights And Small Motors 
Stage 5 witc h board (Manuel Or Remo te Control) 

-'■■Pilot 
Board 

(If Stage 
Switchboard 
Is Remote 
Control) 



’///////A V///S//S77?. 


Stage Lights-, Proscenium ,\ 
Foots, Borders And Pockets : 


■Branches To Dressing ■ 
Rooms, Orchestra, 

Work Lights And Programs 


Fia. 482.—Showing diagrammatically a general scheme of circuit lay-out for theatre 

wiring. 


practically all medium and large-size modern theatres. How¬ 
ever, local conditions may necessitate slight variations from 
this general scheme. The plan as shown consists of three 
separate sets of services: (1) The general-power service, L, which 
supplies the current required for the large motors. (2) The 
emergency service, M, which supplies current for the emergency 
lamps. (3) The general-lighting service, N, which supplies 
current for lighting the stage, auditorium, basement, lobby r 


I 






























































































356 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


■General-Power Service Board 


offices, signs and the like. The circuits employed for dis¬ 
tributing the energy which is supplied by each of these three 
services are discussed in subsequent sections. 

397. The General-power Cabinet (C, Fig. 482) usually 
consists (see Figs. 536 and 552) of a combination of the service- 
entrance equipment—switch, fuses and meter—and the dis¬ 
tribution panel for distributing the energy to the various motors. 

The reason for combining the 
service-entrance equipment 
and the distribution center at 
the same cabinet is because 
the center of the motor load 
is usually near the stage- 
basement, which is also near 
the service entrance. How¬ 
ever, if the center of the 
motor load is far removed 
from the service entrance as 
shown in Fig. 483, the 



i 

: zr> 

X 

ft % 

IJ Auditorium 

Feeder xr 

A r 

D <u ; 

A 

v \ 

O \ 

General-Power Cabinet 

Or Distribution Panel-' 
h( Approximate Center 
y Of Motor Load) j) 

f a $ 
+- / 
vT> ; 

•l 


'General-Power Service 


Fig. 483.—When the center of the motor 
load is located at a considerable distance 
from the service entrance, then the dis¬ 
tribution panel is located near the motor¬ 
load center and connected to the general 
power service board by a set of feeders. 


general-power service board may consist only of the service- 
entrance equipment. In such cases, the power-distribution 
panel ( D , Fig. 483) is located near the center of the motor 
load. Then, it is connected to the power service board, C, by 
a single set of feeders, F. 

398. The Control Panel For The Converter Or Motor- 
generator In The Picture Booth (F } Fig. 482), is fed by a 

separate set of sub-feeders from the general-power cabinet. 
This control panel usually consists of only a sheet steel- 
enclosed externally-operated knife-switch (Fig. 556 -II) which is 
properly fused for the protection of the switch and branches. 

399. The Emergency Service Board (B , Fig. 482) nearly 
always consists of a properly-fused, externally-operated 
enclosed knife-switch (see Fig. 555-/7), provided with 
meter-loops and two sets of connecting lugs. The service 
wires are connected to one set of these lugs. The meter and 
the feeders which supply the emergency distribution panel 
(Sec. 400) are connected to the other set of lugs. The emergency 
service board is, even when the emergency-service entrance 
is at the front of the theatre (Fig. 474), seldom combined with 


















Sec. 400] 


THEATRE CIRCUITS 


357 


the emergency distribution panel. This is because (Sec. 395) 
the emergency-service entrance, and therefore the emergency 
service board are usually in the basement, and the emergency 
distribution panel is (Sec. 401) practically always installed in 
a room which is located on the first floor. 

400. The Emergency Cabinet (E, Fig. 482) is the distribu¬ 
tion center for the current which lights the emergency lamps. 
This cabinet consists (Fig. 546) of an unfused switch and bus¬ 
bars for distributing current to the various plug-fused branches. 
The switch, busbars and fused-connections are mounted on a 
suitable base of non-insulating material—usually slate—and 
the whole is enclosed in a metal cabinet. For a typical 
example of the circuits fed from an emergency cabinet (see 
Sec. 452, Clause 34). 

Note.—The Branch-circuit Connections Of An Emergency 
Cabinet May Or May Not Be Equipped With Branch-circuit 
Switches. It is considered good practice, and a number of the larger 
cities require that these branch-circuit switches be omitted. The reason 
for the omission of these switches is because experience has shown that 
if thej r are provided, the manager will, during an afternoon performance, 
turn off all of the emergency lamps (Sec. 452, Clause 34, E-18) on the 
fire escapes, and in alleyways and courts outside of the theatre proper. 
Then if someone forgets to turn them on for the evening performance and 
a fire or panic occurs, it may be disastrous for the people from the galleries 
and balconies to rush out upon unlighted fire escapes. 

401. The Emergency Cabinet Should Be Located In The 
Front Portion Of The House (see Fig. 531 and Code Rule 38b 
Par. 3). It is usually installed in the lobby, foyer, front- 
doorman’s closet, box office, manager’s office, or in some other 
place which is readily accessible. 

Note.—The Emergency-cabinet Main Switch (Sec. 400) may be of 
a type which is manually operated or remotely controlled. If it is 
a remote-controlled switch, the remotely-controlling momentary- 
contact push switch is usually enclosed in a glass-front cabinet and 
installed on a side wall of the lobby or vestibule (Fig. 531) just inside 
the main doors, (see Code Rule 382.) This glass front cabinet is pro¬ 
vided with a door and a lock, so that only authorized persons may 
normally have access therto. The glass front is sometimes lettered 
with the words, “In Case Of Fire Break Glass And Push The Button 
Then if a fire occurs when no one is in the theatre, the firemen may, by 
operating this momentary-contact switch, light the emergency lamps. 




LIGHTING CIRCUITS AND SWITCHES 


[Drv. 9 


402. The Emergency Lamps Should Be Of Sufficient Rating 
And Should Be So Arranged that, if all other lights fail, they will 
provide a well-lighted pathway from all parts of the theatre 



Outlet 
i Box 


Conduit 


Glass 
In Door 
Above 
Sign ■ 


■Sheet- 
Metal 
Box ' 






I-Front Vi ew 


Fig. 4S4. —Details of exit sign. (The word “Exit” is so rendered on the glass that it 

appears red.) 


to the street. Also, since they must be kept burning during 
the performance, the illumination provided thereby must not 

be excessive or a “dark-house” effect cannot be obtained. 

* 

Experience has shown that one 60-watt lamp, or the equiva- 


.Guard And Reflector 



Cast-Iron Glass Window' 

frame TAisle Lamp 


E-Aisle Lamp 
Mounted On Seat 


Fig. 485.—A 10-watt aisle-lamp fixture connected to the emergency circuit and mounted 

on seat. {The Brookins Co.) 


lent thereof, for each 400 sq. ft. of main-auditorium and 
balcony-floor space (0.15 watts per sq. ft.) will, if properly 
located, meet the above requirements. The lamps within 



































































































































































































































Sec. 402] 


THEATRE CIRCUITS 


359 


the theatre which are connected to the* emergency circuits 
are: (1) Exit-sign lamps (Figs. 484). (2) A sufficient number 

of wall and ceiling lamps in main auditorium, balcony, corridors, 
stairways, foyer, lobby, and all other places within the theatre 
which are generally accessible to the public, to provide at least the 
average wattage per square foot as given above. (3) Aisle 
lamps if any, (Figs. 485, 486 and 487). In addition to the 
above-mentioned lamps, all outside alleyways, courts, or 



Fig. 486.—Showing method of wiring an aisle-light fixture, when aisle lights are 
provided after theatre has been finished. In a new building, the outlet box, B, may 
be installed flush with the floor. 


fire escapes, which may be used by the public in going from 
a theatre exit-door to the street should be well illuminated by 
lamps which are connected to the emergency circuit. 

Note.—Any Emergency Lamp Should Not Have More Than One 
Set Of Fuses (those in panel E, Fig. 482) between it and the main 
emergency-service fuses (those in panel B, Fig. 482). See Code Rule 
38t, Par. 2. 

Note.—Although The Exit-sign Lamps Are On The Emergency 
Circuit, Strictly Speaking They Are Not Emergency Lamps. It is 
only intended that the exit-sign lamps shall act as markers to indicate 






































360 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


the location of the exit doors. The exit-sign lamps are not intended to 
provide any illumination, and therefore are not to be considered in 
computing the total emergency-lamp wattage. In many cities, the exit 
signs must be provided with both gas and electric illumination. In such 
places, if gas is not available, the exit sign must, in addition to the 
electric lamp, be provided with an oil lamp. 



Fig. 487.—Flush type aisle light for stairway or hallway. (Frank Adam Electric Co.) 


403. The General-lighting Cabinet (.A , Fig. 482) usually 
consists (Fig. 535) of a combination of the service-entrance 
equipment—service switch, meter loops, and service fuses— 
and the necessary busbars and fused-connections for the 
various feeders which supply energy to the cabinets that are 
mentioned in the following section. The general-lighting 
service board and the cabinet containing the distribution 
center for the feeder connections may, as suggested in Sec. 
395, be separate and located in different parts of the building. 
However, this is the exception and not the rule. The two are 
usually combined and located (Fig. 530) in the basement under 
the stage. 

404. The Distribution Centers, Or Cabinets, Which Are 
Ordinarily Fed Through Feeders From The General-lighting 
Cabinet are (see Fig. 550): (1) Sign Cabinet. (2) Front- 
doorman's Cabinet. (3) Dressing Room Cabinet , if any. (4) 
Shop Cabinets ,—business places, offices and stores—if any. 
(5) Stage Switchboard. Each of these cabinets and the branch 










































Sec. 405] 


THEATRE CIRCUITS 



circuits which are fed therefrom are described in detail in the 
following sections. 

405. The Sign Cabinet (S, Fig. 482) which serves the electric 
signs and which is fed (Fig. 550) from the general-lighting 
cabinet (Sec. 403) by a separate set of feeders, is usually located 
along side of the front doorman’s cabinet (Sec. 406). How¬ 
ever, in some installations which have a heavy sign-lighting 
load, the center of which is far above the street level, it may be 
more economical to install the sign cabinet (S, Fig. 488) in 
some suitable place on the third or fourth floor near the 



Sign Cabinet- 


Converter Cabinet - - - _. 
Gal/erg 

„ Picture 

Booth -.. 

Picture-Booth Cabinet . 

Balcony 


a BBSS 


Phot 

Board- 


■Remote 

board 


Doormans Cabinet- 
Emergency Cabinet- 


. -Power 
Cabinet 






Shop Cabinet 
Gener a! Power Cabinet 


Elevator-Control Cabinet- 


•*£ • -Pent 
House 


'Generals ighting Cabinet 
'-Emergency Service Board 


Fig. 488.—Riser diagram for combined theatre and office building. 


sign load center. In such an installation, the sign-cabinet 
switches are usually of the remote-controlled type. Then, 
the sign cabinet is fed by a direct feeder from the general¬ 
lighting cabinet, and only the necessary control wires for the 
remote-controlled switches are run from the sign cabinet to the 
controlling momentary-contact switches which are installed 
in the box office, manager’s office, or in the trim of the front- 
doorman’s cabinet. The design of the sign cabinet will 
depend upon the signs which are to be served. In general, 
this cabinet consists (Fig. 547) of the busbars, and a number 
of knife or remote-controlled switches, each of which controls 






































































LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


362 


a number of fused 660- or 1,320-watt branch circuits. The 
sign cabinet serves (Sec. 452, Clause 36) such signs outside 
the building as the roof signs, outside-entrance canopy lamps, 
attraction signs, and the like. 

406. The Front-doorman’s Cabinet (or Lobby Cabinet, 

G, Fig. 482) is usually located (Fig. 531) somewhere in the 
front portion of the theatre near the lobby or foyer, and pref¬ 
erably in a room which is near the front-doorman’s station, 
such as the front-doorman’s closet, the check room or some 
similar place. This cabinet is generally provided (Fig. 545) 
with an unfused main switch and bus-bars which feed the 
required number of 660- or 1,320-watt plug-fused branch cir¬ 
cuits. Each of these branch circuits is generally equipped 
with a branch-circuit switch. These branch circuits serve 
all lamps which are used for general illumination in the front 
portion of the theatre (Sec. 452, Clause 32), such as the lights 
in the lobbys, foyers, canopy, picture booth, corridors, stair¬ 
ways, ladies’ and men’s parlors, check rooms, box office, 
manager’s office, ushers’ rooms, janitors’ closet, and the * 
like. The front-doorman’s cabinet is sometimes called the 
lobby cabinet. For a typical example of the circuits served 
by the front-doorman’s cabinet, (see Sec. 452, Clause 32). 

Note.—Some Of The Branch Circuits Of The Front-doorman’s 
Cabinet Should Be So Connected Ahead Of The Main Switch that 
they will not be disconnected from the energy source when the main 
switch is open. In general, the branches which should be so connected 
(Sec. 452, Clause 31) are those which serve the picture-booth cabinet, 
the lights in the manager’s office, box office, ushers’ rooms and janitors’ 
closets. The reason for this is that the above mentioned circuits may be 
switched on by their individual branch-circuit switches without having 
to close the cabinet main switch. If it is necessary to close the main 
switch of the front-doorman’s cabinet to light the above-mentioned 
places, the janitors or ushers will, when entering the building during 
the day, close the main switch and fail to turn off the other branches which 
are in this cabinet, thus causing a large energy-waste. 

407. The Picture-booth Cabinet, (0, Fig. 482) which is 
located (Fig. 531) in the picture booth, is fed by a set of sub¬ 
feeders—usually two No. 12 wires— from the front-doorman’s 
cabinet (Sec. 452, Clause 39). The picture-booth cabinet 
usually consists (Fig. 548) of a four-circuit panel, each branch- 


Sec. 40SJ 


THE A TRE Cl RC UITS 


363 


circuit connection being provided with a set of fuses and a 
switch. One of these branches serves the lamps for lighting 
the picture booth and the converter room. The other three 
branches usually serve the two picture-machine motors and 
the rewind motor. 

408. A Profitable Current-saving May Sometimes Be 
Effected By A Careful Selection Of The Circuits To Which 
Those Lamps In The Front Portion Of The Building Are 
Connected. For example, if the lamps in the lobby and 
on the canopy are properly divided (see Sec. 452; Clause 
34, E -1 and E- 2; Clause 32, G-l, G- 2, G- 6, G -7 and G -37 to G- 42; 
and Clause 36, $-1 and $-3) between the emergency cabinet, 
the front-doorman\s cabinet and the sign cabinet, it may be 
profitable, after the performance is well under way to turn 
out some of the lamps in the front part of the building. That 
is, turn out some of the outside entrance-canopy lamps which 
are served from the sign cabinet, or turn out some of the 
canopy or lobby lamps which are served from the front-door¬ 
man’s cabinet. Then, the lamps which are on the emergency 
circuit, and those that are served by the front-doorman’s 
cabinet and the sign cabinet which have not been turned out, 
must give the desired illumination for this portion of the 
building. 

409. A Dressing-rcom Cabinet is sometimes used in those 
installations where there are a large number of dressing- 
rooms. When used, this cabinet is ordinarily installed in the 
stage-doorman’s closet. This cabinet should consist of a 
cabinet main switch, the busbars for feeding the required 
number of 660-watt fused branch-circuit connections, and 
branch-circuit switches. This cabinet serves the lights in 
the dressing rooms, musicians’ rooms, furnace room, passage 
ways, and all other parts of the stage basement. When a 
dressing-room cabinet is provided, it is fed and controlled 
(see switch No. 25, Fig. 500) from the stage switchboard. 
In installations where a dressing-room cabinet is not used, 
the distribution center for these circuits is (Sec. 452, Clause 
28) at the stage switchboard, from whence they are controlled. 

410. A Shop Cabinet (/, Fig. 488) is usually employed to 
feed the shops or offices which may be contained in the theatre 


364 LIGHTING CIRCUITS AND SWITCHES [Div. 9 

building. This cabinet, which is located (Sec. 452, Clauses 
44, 45 and 46) near the shop load, is fed (Fig. 550) by a sepa¬ 
rate set of feeders from the general-lighting cabinet (A, Fig. 
488). If the owner of the building furnishes light to the 
tenants, all of the power used for lighting the building is 
usually metered at A, Fig. 488. Thus, the power can usually 
be purchased at a lower rate, than if the lighting power which 
is used by the tenants is metered separately. However, if 
each tenant pays for his own power, the feeder which supplies 
J may be connected (Fig. 535, circuits 2 and 3) ahead of the 
meter loops at A, Fig. 488. Then a separate meter for each 
tenant is connected into the various sub-feeders at J. A 
separate distribution panel, K, which is fed from J, is then 
provided for each tenant. 

411. The Stage Switchboard (D , Fig. 482) is fed from the 
general-lighting cabinet. The terminology, types, and cir¬ 
cuits of stage switchboards will now be treated. 

412. The Lights Which Are Generally Controlled From 
The Stage Switchboard May Be Classified as: (1) The house 
lights. (2) The stage lights. (3) The work lights. Each of 
these terms is hereinafter defined. 

413. The House Lights (see Sec. 452, Clause 30, D-38 to 
D-48) are those lights which are used for the general and 
decorative illumination of the auditorium and balcony. 
These lights are usually of one color, or of three colors. If the 
house lights are of only one color, they are usually white or 
amber. If there is more than one color of house lights, the 
colors which are provided are usually white or amber, blue, 
and red. In such a three-color installation, the sum of the 
number of the blue lamps and the red lamps is practically 
always equal to the number of white lamps. However, 
sometimes the house lights consist of equal numbers of white 
or amber, red, and blue lamps. 

414. The Stage Lights are those lights (see Sec. 452, Clause 
30, D -2 to D-36) which are used to provide the illumination 
and the decorative effect of a scene on the stage. The princi¬ 
pal stage lights consist of: (1) The footlights. (2) The 
proscenium lights. (3) The border lights. (4) The arc and 
incandescent pocket lights. Frequently other stage lights are 


Sec. 415] 


THEATRE CIRCUITS 


365 


provided, such as spot lights located in the ceiling over the 
orchestra pit. The stage lights nearly always consist of three 
colors; white, red, and blue, in the same proportions as that 
given in Sec. 413 for the house lights. 

Note.—The Number, Wattage, And Locations Of The Various 
Stage Lights for proper illumination of stages of different dimensions 
may be determined from the data as tabulated in Figs. 488A and 488B. 
These illustrations are self-explanatory. 


g-'-For 4 Color These Lamps To Alternate White And Amber 


> 

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r- 

5 a- 

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£ * 
f E 

X a 

LD —1 

White foots Total Watts 

50 Watt Red 

Lamps 6"CToC 

Red Foots Total Watts 

50 Watt blue 

Lamps 6" C To C 

blue Foots Total Watts 

j 

3-Color 


4- 

Color 


4- 

V 

£ 

a 
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4- 

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20 

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3,200 

32 

1,600 

32 

1,600 

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25 

21 

84 

4,200 

42 

2,100 

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5,000 

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6,000 

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3,000 

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3,000 

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54 

156 

6,600 

68 

3,400 

68 

3,400 

28 

6 

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2,700 

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33 

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2,400 

8 

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59 

156 

7,600 

78 

3,900 

78 

3300 

34 

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37 

4 

l 

2,700 

9 

50 

43 

172 

6,600 

86 

4,300 

86 

4,300 

37 

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3,600 

12 

41 

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55 

48 

192 

9,600 

96 

4,800 

96 

4,800 

44 

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208 

10,400 

104 

5,200 

104 

5200 

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15 

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65 

57 

228 

11,400 

114 

5,700 

114 

5,700 

53 

6 

2 

5,100 

17 

54 

5 7L 

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3,900 

13 

70 

62 

248 

12,400 

124 

6,200 

124 

6,200 

59 

5 'k 

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5,700 

19 

58 

6 

2 

4,200 

14 

75 

67 

268 

13,400 

134 

6,700 

134 

6,700 

62 

6'k 

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6,000 

20 

62 

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15 

60 

71 

264 

14,200 

142 

7,100 

142 

7,100 

68 

6 

2 

6,600 

22 

66 

7 

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4,800 

16 

85 

76 

504 

15(200 

152 

7,600 

152 

7,600 

74 

5 'h 

2 

7.200 

24 

74 

5'A 

2 

5,400 

18 

90 

60 

320 

16,000 

160 

8,000 

160 

8,000 

60 

5 

2 

7,800 

26 

78 

6 

2 

5,700 

19 

95 

84 

536 

16800 

168 

8,400 

168 

8,400 

63 

6 

2 

6100 

27 

82 

674 

2 

6,000 

20 

100 

84 

356 

16,800 

168 

6,4001 

168 

8,400 

86 

7 

2 

8,400 

26 

86 

7 

2 

6,300 

21 


Fig. 48SA.—Chart showing numbers of and wattage of lamps for foot and border 
lights for stages, based on depth of stage and width of proscenium opening as indicated 
in Fig. 488B. (Copyright by Frank Adam Electric Co., St. Louis, Mo.) 


415. The Work Lights (see Sec. 452, Clause 28) are all of 
those lights, that are controlled from the stage switchboard, 
which are used to provide illumination for the theatre 
employees. The work lights generally consist of the orchestra 
lights, gridiron lights, fly-gallery lights, dressing-room lights, 
bracket lights located on the walls back of the stage, and the 
like. All of the work lights are white lights. The gridiron 
or rigging loft is the open floor formed by the horizontal frame¬ 
work which carries the pulleys over which the lines pass 

































































LIGHTING CIRCUITS AND SWITCHES 


IDiv. 0 


366 


whereby the drops, border lights and the like are raised and 
lowered. The gridiron occupies the space over the stage near 
the roof. 



Fig. 488B.—Diagram of stage and proscenium for dimensions which are tabulated in 
Fig. 488A. ( Copyright by Frank Adam Electric Co, St. Louis, Missouri.) 

416. The Following Are Definitions Which Relate Specifi¬ 
cally To Stage Switchboards And The Circuits Controlled 
Therefrom: 

A Remote-control Switchboard is a complete equipment whereby 
switching is effected by remote-controlled switches. An electrically- 




















































Sec. 416] 


THE A THE CIRC UITS 


367 


operated remote-control switchboard comprises two essential elements: 
(1) The pilot board (Fig. 507). (2) The remote board (Fig. 508). 

A Remote Board (Fig. 508) is an equipment comprising remote- 
controlled switches, the required busbars, and the supporting structure. 
A remote board, usually consists of a structural steel frame, on which are 
mounted the remote-controlled switches, together with the necessary 
wiring and busbars for connecting the remote-controlled switches with 
the circuits controlled by them. When the board is not installed in a 
fireproof room or vault, it is enclosed in a sheet steel cabinet which can be 
locked. 



Fig. 489.—Diagram to illustrate stage switchboard nomenclature. All of the sub¬ 
feeders which feed house and stage circuits feed through magazine panels as shown above 
at P. 


The Stage Switchboard Feeders (A , Fig. 489) are the conductors 
which connect the general-lighting cabinet to the stage switchboard bus¬ 
bars. 

The Stage-main Switch Or “Stage Main” is the switch ( S , Fig. 
489) through which all of the current flows for lighting the stage lights 
(Sec. 414). Thus, when the “stage main” is open none of the stage 
lights can be illuminated. This switch is also sometimes called the 
stage-master switch or the stage-bull switch. 

The House-main Switch Or “House Main” (H , Fig. 489) is the 
switch through which all of the current flows for lighting the house lights 
(Sec. 413). This switch is also called the house-master switch and the 
house-bull switch. 

A Color-main Switch Or “Color Main” (IF, R, and B, Fig. 489) is a 
switch through which all of the current flows for lighting the stage lights 


















































368 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


(Sec. 414) or the house lights (Sec. 413) of any one color. Thus, if the 
‘'white main” (IF, Fig. 493) is open, none of the lights—“stage whites”— 
which are controlled by switches Nos. 10, 7, 4, 1, 16 and 13 (Fig. 493) 
can be lighted. Color main switches are usually provided on a manually- 
operated (Sec. 423) non-interlocking switchboard. On a manually- 
operated interlocking switchboard (Sec. 424), the function of a 
color-main switch is performed by a master lever ( B , R, and IF, Fig. 
494). A color-main switch is also sometimes called a color-master switch , 
or a bull switch. 

A Magazine Switch (M , Fig. 489) is a switch through which all of the 
current flows for lighting the lamps which are connected to one section 
of the magazine panel. 

A Magazine Sub-feeder (L, Fig. 489) is a set of conductors extending 
between a magazine switch and a magazine panel and through which 
electrical energy is supplied to a section of the magazine panel. 

A Magazine Panel (P, Fig. 489) is a distributing panel for such 660-or 
1,320-watt branch circuits as are fed through the magazine switches of the 
stage switchboard. Thus a magazine panel comprises the bus-bars, C 
and the branch-circuit fuses, E, through which the magazine circuits are 
fed. 

A Magazine Circuit (Fig. 489) comprises all of the 660-or 1,320-watt 
branch circuits, which serve the various outlets that connect to the bus¬ 
bars of one section of the magazine panel. A magazine circuit may 
consist of only one 660- or 1,320-watt branch circuit. 

A Pilot Board (Fig. 507) is the switchboard, in a remote-control 
installation, which comprises the pilot switches, the inter-connecting 
conductors between the pilot switches and the supporting structure for 
both. 

An Individual Pilot Switch (Fig. 510) is a switch on a pilot board 
which is so connected that it can be used only to control the electromagnet 
circuits of one remote-controlled switch. A pilot switch is a remotely- 
controlling switch. 

A Sub-master Pilot Switch is a pilot switch which is so connected 
that it may be used to control the electromagnet circuits of two or more 
remote-controlled switches. 

A Master-pilot Switch is a pilot switch which is so connected that it 
may be used to control the circuits of two or more sub-master pilot 
switches. 

The Constant-circuit Switches (Fig. 519) on a stage switchboard 
are the switches, which open or close the circuits to the rigging-loft, 
orchestra, attic and sometimes the dressing-room lights, and the lights 
in other places where stage or auditorium lighting effects are not required. 
The circuits which these constant-circuit switches open and close are not 
fed through the “main” switch, if any, and are not controllable by a 
pilot switch if any (see Sec. 415). The work lights are controlled by 
constant-circuit switches. 


Sec. 417] 


THEATRE CIRCUITS 


369 


417. The General Scheme Of Circuit Control Which Is 
Usually Provided On All Stage Switchboards is indicated in 
Fig. 490. Nearly all theatre stage switchboards control 
more circuits than are shown in Fig. 490. For example there 
may be three borders, instead of only one, as shown. If 
there were, say, three borders, the white lights of borders 
Nos. 2 and 3 would be provided with a separate magazine- 
panel section, dimmer, and magazine switch, and would be 


Dimmer Bank Usually Mounted On .. n . „ . .. , , 

Top Of Or Behind Stage Switchboards (Magazine-Panel Board Mounted 

, / . fiG ht / yard Vt/v/vo iiv/r^nri/i/vr'/V 

Stage Switchboard--..^ k 

. v| 


\ Behind Stage Switchboard 

A. 



House- 
Main ; 

P 

[For House 
' Lights ' 

For Work 
Lights < 
V 


/7y^VA.W\l . ; . 

TvjvAWLi.: - | ; ..'J. j . 

, » I 1 "V» -Q-Q— 


/a/'J’WvwJ • 


Lamps- 




.■ .y j 


White Foots 
" Proscenium 
" Border No.l 

: Red Foots 

Proscenium 

Border No.l 

:Blue Foots 

" Proscenium 

" Border No.l 

The Number Of 
These Circuits Will 
^Usually Depend Up¬ 
on The 5iie And. 
Architectural Design 
Of The Theater. 


-o—o- Orchestra 




o—o- Dressing Rooms 


o—o-Gridiron & fly Gallery 
o-o-5tage Work Lights 
o—a—Boiler Room 


Magazine•/ 

Panels' 

Fig. 490.—Illustrating the general scheme of circuit control which is usually provided 

on stage switchboards. 


connected in a manner similar to that for Border No. 1. If 
the house lights consist of three colors, the house circuit would 
be subdivided according to colors in a manner similar to that 
employed for the stage circuit. For specific examples of 
actual stage switchboards, see subsequent sections. 

418. The Requirements Of Stage Switchboards Are Very 
Exacting. The currents which must be handled are relatively 
large. Furthermore, space on the stage at the side of the 
proscenium arch where the switchboard must always be located 

is at a premium. Therefore, it is essential that the switch- 

24 


































































































370 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 0 


board equipment be compacted into minimum space (Fig. 
490A). Also, every precaution must be taken to insure that 
the stage switchboard will function properly at all times. If 
it should fail while a show was in progress, the result would 
be commercially disastrous. 

Note.—Flexibility Of Control Is Probably The Most Exacting 
Operating Requirement Of A Stage Switchboard. That is, the 
design and construction of the board should be such that the stage elec¬ 
trician can instantly switch in or out of service any combination of any of 



^ To Service Through 
Oenerai Lighting Cabinet 


Conduits 


-rs 

(nC« 

(V, s Q 


T'Shaped Pul/Box^ ^-Sug gested Min. 
Or Wire Duct 


'f -Dtmm c-r 5 


Connecting 

■Busbars',* 




White 


<U o 


c 




r-» 


P>.N> 


Blue 


Amber 


i n 


ruse 


;Magazine 
Snitch,Open 




I-End View Of 
Switchboard And 
Dimmer Bank 


-Channel When Specified 

H- Perspective View Of Switchboard And 
Magazine Panel 


Wall Between 
'Stage And 
Auditorium 


Fig. 490A.—Installation arrangement of stage switchboard and magazine panel as 
recommended by the Mutual Electric & Machine Co. (The cables from the general- 
lighting cabinet usually run to the main-house and main-stage switches from whence the 
current is then conducted through busbars to the magazine switches, then through the 
wiring channel to the dimmers and from there to the magazine panel or direct to 
the circuits controlled.) 


the house and stage lights. This may involve a change in the color of 
the light. Also, the design should be such that he can gradually 
change the brightness of any combination of any house or stage lights by 
using the dimmers. 

419. The Location Of The Stage Switchboard is usually at 
the right-hand side of the proscenium arch when standing on 
the stage facing the audience (see Fig. 531). The reason for 
such location is that most of the portable lighting equipment 
that is carried by travelling companies is made “ right- 
handed.^” That is, when the portable equipment is placed on 
the stage facing the audience, the leads connecting to it are 

































































Sec. 420] 


THE A TRE CIRC VITS 


371 


on its right-hand side. In some theatres, the stage switch¬ 
board is, because of space or other limitations, installed at the 
left-hand side of the proscenium. This location is the excep¬ 
tion rather than the rule. 

420. Theatre Stage Switchboards May Be Either “Live 
Front” Or “Dead Front.” However since the Code (Rule 
38c) now prohibits the installation of live-front stage switch¬ 
boards, it is not probable that they will ever again be used in 
this country. Therefore, the following material in this book 
will treat exclusively of dead-front switchboards. 

Note. —The Stage Switchboard For Small Moving Picture 
Houses May Sometimes Be A Live-front Board Provided It Is 
Enclosed In A Steel Cabinet. The following paragraph, by H. S. 
Wynkoop, Chief Electrical Inspector, New York City, which explains 
the practice in New York City, probably exemplifies the practice of 
electrical inspection bureaus of other cities: 

“Literally, the Code requires dead-front switchboards for moving 
picture establishments, even if there is no stage. We draw a distinction, 
however, between such a house and one which has movable borders, 
footlights, proscenium side-strips, stage pockets and other facilities for 
staging a regular dramatic or operatic performance. In the mere picture 
house, with its footlights and lights outlining the proscenium arch, 
there is no point in calling for a dead-front switchboard; and in fact the 
switchboard reduces itself to a simple panel inclosed in a cabinet. A 
third class of house with which we have to deal includes lecture halls and 
school auditoriums. If the stages of these rooms are equipped for the 
giving of operatic or dramatic shows, we class them as theatres; but if, as 
is usually the case, they are not so equipped, and are used a few times a 
year for amateur theatricals, additional and temporary wiring is per¬ 
mitted under close supervision, and this wiring is taken from the panel 
board.” 

421. Stage Switchboards May Be Either of The Manual 
Type Or Of The Remote-control Type. A manual switchboard 
is one, the lighting switches of which are mounted directly on 
or behind the board itself, and operated directly by the hand. 
A remote-control switchboard is one, the lighting switches— 
remote-controlled switches, Div. 8—of which are located in a 
convenient place remote from the control switchboard—pilot 
board—and which are operated therefrom electrically by 
suitable control switches—pilot switches—which are mounted 
on the pilot board. 


372 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


Note. — Theoretically , Remote-control Switchboards May he Remotely 
Controlled Either Mechanically or Electrically. In a mechanical remote- 
control board, the lighting-circuit switches would be located at some 
point distant from the control board itself and operated therefrom, 
through a system of links and levers, just as is done (Sec. 315) for mechan¬ 
ical remote control of power and lighting switchboards. The ease and 
flexibility of control, which is provided by the electrically-operated remote 
control board would not be possible with a mechanically operated one. 

422. Manually-operated Dead-front Stage Switchboards 
May Be Classified According To Construction as: (1) Non- 



Fig. 491. Front view of non-interlocking, dead-front manually-operated stage 
switchboard. (Mfr’d. by The Trumbull Electric Mfg. Co. for the Beacham Theatre 
Orlando, Fla.) 

interlocking. (2) Interlocking. A non-interlocking board is 
one wherein each individual switch must be operated sepa¬ 
rately and independently of every other switch on the board. 
However, a board of this type is usually so wired (Sec. 423) 
that the lamps which are controlled by a number of magazine 
switches (M, Fig. 489) may be simultaneously lighted or 











Sec. 423J 


THEATRE CIRCUITS 


373 



extinguished by a “main” switch (W, R or B, Fig. 489). 
An interlocking board is one wherein the various magazine 
switches (M, Fig. 489) may be mechanically interlocked to a 
shaft. Then, upon operating this shaft by means of a master 
lever, those magazine switches which have been interlocked 
therewith, may be simultaneously opened or closed. Thus, 
those lamp-groups which are controlled by the magazine 
switches that have been so interlocked may be simultaneously 
lighted or extinguished. The mechanical construction of 


Fig. 492.—Rear view of non-interlocking, dead-front, manually-operated stage 
switchboard. (Mfr’d. by The Trumbull Electric Mfy. Cu. for the Beacham Theatre, 
Orlando, Fla.) 

switches and operating mechanisms which are used on certain 
dead-front manually-operated switchboards is explained and 
illustrated in Sec. 427. 

423. A Typical Non-interlocking, Dead-front, Manually- 
operated Stage Switchboard is shown in Figs. 491 and 492. 
The wiring diagram and schedule of connections is shown in 
Fig. 493. The dimmers, which are mounted above the 
switchboard, are not shown. 


B usb ar s - — ^ , - - -^-Dimmer Lugs 




li 


70 




mum. , 


MM 


r"!6 IJ 18X11X42 4', 40 39 33; 


White / 
d Main 


Mam 


Blue 


Channel 

Support- 


Iron 


Mam 


Red 

























SCHEDULE 


374 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 




Fig. 493.—Wiring diagram of non-interlocking, dead-front manually-operated stage switchboard. Full lines indicate busbars. Dotted lines indicate 
rubber-covered copper conductors. (Mfr’d. by The Trumbull Electric Mfg. Co. for The Beacham Theatre, Orlando, Fla.) 





















































































































































































































































Sec. 424]. 


THEATRE CIRCUITS 


375 


424. An Interlocking, Dead-front, Manually-operated Stage 
Switchboard is shown in Figs. 494, 495, and 496. The 
switchboard wiring diagram is shown in Fig. 497. As indi¬ 
cated in Fig. 497, the stage lights that are controlled by 



SCHEDULE 


'.fc ■ 

a 

X 6 

CONTROLS 

-C 
u . 
o 

i z 

CONTROLS 


CONTROLS 

l 

Main Ceiling? Mo. / 

16 

Red border No. / 

31 

Stage Pockets 

2 

'/ // n 2 

17 

It 

// 

No. 2 

32 

tt // 

3 

Orchestra Ceiling? 

18 

n 

tt 

No. 3 

33 

Orchestra Plugs 

4 

n Walls 

19 

// 

// 

No. 4 

34 

It // 

5 

balcony n 

20 

blue 

Foots 

35 

Stage Chandelier 

6 

box // 

21 

// 

border No.! 

36 

balcony 

7 

n Ceilings 

22 

// 

n 

No. 2 

37 

Picture booth 

8 

Tor men tor 

23 

// 

It 

No. 3 

38 

Stage Wall Cabinet 

9 

White Foots 

24 

u 

n 

No. 4 

39 

Fly Gallery 

10 

White border No. i 

25 

Stage Rochets 

40 

For Future Use 

II 

// // No. 2 

26 

It 


It 

41 

II tt It 

12 

n // No- 3 

27 

// 


ft 

42 

" // // 

13 

n n No. 4 

28 

// 


1/ 

43 

II tt tt 

14 

Procenium Strip 

29 

ft 


It 

44 

// It // 

15 

Red Foots 

30 

ft 


// 

45 

Main Stage 


Fig. 494. —Front view of interlocking, dead-front, manually-operated stage switch¬ 
board. (Manufactured by the Pringle Electrical Mfg. Co. for the Hippodrome Theatre, 
Buffalo, N. Y.) 

switches Nos. 8 to 24, inclusive, may be extinguished by open¬ 
ing the stage-main switch, No. 45. That is, switch No. 45 
controls all of the switches Nos. 8 to 24, inclusive. Any or all 
of the switches No. 20 to 24 which control the blue stage 














































































































376 


LIGHTING CIRCUITS AND SWITCHES 


. (Div. 9 


H k-- INDEPENDENTS-X. - POCKETS 


INDEPENDENTS 


-g'-o"-- 


—H 


J .11 ! l M :l IJ j J J IJ J J J; j J 

Y£HOOA->\ (<- 100-200Amp. - >\ 


35 34 33 


130 

a a 

31 



A. 100 A 




100 A. 100 A. 



3a 


39 


40 


41 



HOUSE 


0-30 A:" 



$ 





f--' ■ .,. 


No+e 


'All Switches Not 
Otherwise Specified 
lOOAmp. But Arrang¬ 
ed For N.E.C. Standard 
Fuses As Shown. 


'** 

CM 


■/////s/S. //// 


--— 


Fig. 495. —Rear view of interlocking, dead-front, manually operated stage switch¬ 
board showing dimensions, fuse and switch sizes. (Manufactured by The Pringle 
Electrical Mfg. Co. for the Hippodrome Theatre, Buffalo, N. Y.) 



Fig. 496. Rear view of interlocking, dead-front, manually-operated stage switch¬ 
board showing busbar construction. (Manufactured by The Pringle Electrical Mfg. 
Co. for the Hippodrome Theatre, Buffalo, N. Y.) 

















































































































































Sec. 425] 


THEATRE CIRCUITS 


377 


lights, may be simultaneously opened or closed by interlocking 
them on the shaft and then operating the blue master lever, 
B (Fig. 494). Similarly, the red stage lights, the white stage 
lights, the stage-pockets, and the house lights may be con¬ 
trolled, respectively, by their master levers, R, W, A and H, 
Fig. 494. No master handle is provided for the independents— 
switches Nos. 33 to 44, inclusive; consequently, to light or 
extinguish the lamps which are controlled by these switches, 
each switch must be individually and separately operated. 



Feeders From General- 
Lighting Cabinet- .. 


Stage Whites- - 


Fig. 497.—Wiring diagram of interlocking, dead-front, manually-operated stage 
switchboard. (Manufactured by The Pringle Electrical Mfg. Co. for the Hippodrome 
Theatre, Buffalo, N. Y.) 


Note. —A Similarity In The Controls Which Are Provided By 
The Non-interlocking Switchboards may be noted by a comparison 
of the wiring diagram of Fig. 493 and the front view of Fig. 494. That is, 
the white main, IF; Fig. 493, and the master lever, IF, Fig. 494, control 
the stage white lights. The red main, R , Fig. 493, and the master lever, 
R, Fig. 494, control the stage red lights. The blue main, B, Fig. 493, 
and the master lever, B, Fig. 494, control the stage blue lights. Switch 
SM, Fig. 493, and switch No. 45, Fig. 494, control all stage lights. 
Switch RC 5 (Fig. 493) and master lever H (Fig. 494) control the house 
lights. Switches Nos. 19 to 27, inclusive, (Fig. 493) correspond to the 
independents—switches 33 to 44—of Fig. 494. Hence, from the above 
comparison, it is seen that essentially the same control is provided by the 
electrical connections of Fig. 493 as that which is provided by the mechan¬ 
ical interlocking mechanism of Fig. 494. 

425. An Interlocking, Manually-operated Stage Switch¬ 
board Which Is Provided With A Grand-master Lever is 





























































‘ 378 LIGHTING CIRCUITS AND SWITCHES [Div. 9 

shown in Fig. 498. The wiring diagram and the control 
schedule for this switchboard are shown in Figs. 499 and 500. 
Any or all switches in each horizontal row of magazine switches 
(Fig. 498) may be interlocked so that they can be operated by 
their respective master levers, W, B, R or H, for that row. 



C rose connecting 
Duct yy 


Clutch For Inter locking With 

Grand -Fluster Lever Link 

» 

Switchboard 
Lump, 


Fluster A. 
Levers 


Shaft- - - 

dm 


Link 


Grand- 
Mast er 
Lever 


Fig. 498.—Interlocking dead front switchboard for Bay Ridge Theatre, Brooklyn, 
N. Y., provided with master and grand master levers. (Sprague Electric Wor&s.) 


Furthermore, the clutches C, may be so set that either one or 
all of the three upper horizontal shafts will be interlocked with 
the link, L. Then, by operating the grand-master lever, G, 
those magazine switches which are so interlocked to the hori¬ 
zontal shafts may be either opened or closed. 














Sec. 426] 


THEA THE CIRCUITS 


379 


Example. Assume that a scene opens with the white foots, and white 
left and right prosceniums, white border No. 1, blue borders Nos. 2 and 
3, and red border No. 4. At a certain cue all stage lights are to be 
extinguished except the white foots and white border No. 1. The stage 
electrician locks all three clutches, C, to the link, L. He then interlocks 
magazine switches (Figs. 498 and 500) Nos. 1, 9, 10 and 16 with their 
respective shafts. A hen upon receiving the cue, he pulls the grand- 



Fig. 499.—Rear view wiring diagram of interlocking stage switchboard (Manufactured 
by The Sprague Electric Works for Bay Ridge Theatre, Brooklyn, N. Y.) 

master lever, G. This extinguishes the left and right prosceniums, blue 
borders Nos. 2 and 3, and red border No. 4, leaving only the white foots 
and white border No. 1 lighted. 

426. A Manually-operated, Interlocking Stage Switchboard 
Provided With Pre-set Master Levers is shown in Fig. 501. 
As indicated in Fig. 501, this switchboard is also provided 
with a grand-inaster lever. Each horizontal shaft consists 
of a u shaft within a shaft. ” The mechanism is so constructed 






























































































































380 LIGHTING CIRCUITS AND SWITCHES [Div. 9 

that the magazine switches, M, may be interlocked with either 
of these shafts. Master lever A operates one shaft, and master 
lever B operates the other shaft. Hence, three of the maga¬ 
zine switches, M, may be interlocked with the shaft which is 
operated by A, and the other three switches between A and B 
may be interlocked with the shaft which is operated by B. 
Then, by simultaneously pulling downward on A and pushing 


Switch 

Number 

Number 

Of Poles 

Switch 

Capacity 

Fuse 

Capacity 

Ug 

Size 

Controls 

/ 

2 

100 

10 

12 

Pros. L & R. 

2 

2 

too 

35 

8 

White hoots. 

3 

2 

100 

35 

8 

" border No ./ 

4 

2 

too 

35 

8 

No-2 

5 

1 

too 

35 

8 

No3 

6 

l 

too 

35 

8 

•• " No.4 

1 

2 

100 

12 

12 

blue Foots. 

8 

2 

too 

12 

12 

•• border No.l 

9 

2 

100 

12 

12 

No. 2 

10 

2 

100 

12 

12 

No.3 

II 

2 

100 

12 

12 

•• “ No.4 

12 

2 

too 

12 

12 

Red Foots. 

13 

2 

too 

12 

12 

•• border Not 

14 

2 

100 

12 

12 

” Nol 

15 

2 

100 

12 

12 

No.3 

16 

2 

100 

12 

12 

•• " No.4 

n 

2 

too 

10 

12 

Sidelights 

18 

2 

100 

to 

12 

boxes L.8c R. 

19 

2 

100 

35 

8 

Main Chandelier 

10 

2 

100 

25 

10 

Orch. 8t bate. Ceil. 

11 

1 

100 

20 

12 

Fans 

11 

3 

100 

75 

3 

inc. Pockets 

13 

2 

too 

10 

12 

Musicians 

14 

2 

too 

70 

4 

Work Panel 

25 

2 

100 

50 

6 

Dres. Room Panel 

26 

3 

200 

175 

000 

Arc Pockets 

27 

2 

100 

35 

8 

Stage Chandelier 


Fig/500. —Control schedule for stage switchboard in Bay Ridge Theatre, Brooklyn, 

N. Y. (Sprague Electric Works.) 

upward on B, any of the switches may be closed and the 
remainder of the switches opened at the same time. Thus, 
with a board of this type, it is sometimes possible for the 
switchboard operator to so pre-set the switches that a lighting 
change can be instantly effected by operating one or more of the 
master levers. Furthermore, this switchboard is provided 



































Sec. 426A] 


THEATRE CIRCUITS 


381 


with a grand-master lever, which operates the same shafts as 
those which are operated by the master levers, B. Thus, by 
interlocking switches M with the shaft which is operated by B, 
the grand-master lever may be used to simultaneously open 
or close any desired number of magazine switches in two or 
more horizontal rows. 



Fig. 501.— Interlocking, dead-front, manually-operated stage switchboard pro¬ 
vided with grand-master lever and “Pre-set” master levers. ( Metropolitan Electric 
Mfg. Co.) 

Note. —The Relative Location Of The Dimmers, Switchboard 
And Magazine Panel For A Typical Manually-operatfd Stage- 
switchboard Installation is shown in Fig. 502. The dimmer bank is 
usually mounted above the switchboard. In large installations where 
sufficient space is available, the dimmer bank is sometimes located at 
the side of the stage switchboard. The magazine panel is located in 
rear of the switchboard. Sufficient space must be provided between the 
switch board and magazine panel so that fuse replacements may be 
readily made. The sheet-steel cross-connecting duct , D, sometimes called 
a tangle-box raceway, -pull box or merely raceway is located directly behind 
the top of the switchboard and bridges the space between the board 
and the top of the magazine cabinet. The function of the cross-connect¬ 
ing duct is to provide a single metal raceway for all of the conductors 
which run from lighting-circuit switched on the switchboard to the 
magazine-panel cabinet. 

426A. A Manually-operated Pre-set Dead-front Stage 
Switchboard is illustrated in Fig. 502A. The pre-selective 
feature (Sec. 430) is provided by the construction of the 










382 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


magazine-switch lever mechanism (Fig. 502B). Switch¬ 
boards of this type are regularly manufactured with any 


Grand- 2- 
Master 
Slow- / 
Motion 
Dimmer 
Handle 



Switch 

Handles 


V. : •.y-v;V;f 


Fia. 502.—End view of manually operated stage switchboard showing relative positions 
of switchboard, dimmers, and magazine panel. (Electrical Mfg. Co.) 


desired number of switches arranged, usually, in three or 
four horizontal rows. When so constructed, they may be 












































































Sec. 426A] 


THEATRE CIRCUITS 


383 


equipped with a grand master lever which may be operated 
to control any of the magazine switches on the switchboard. 
The principle of operation of such a switchboard is explained 
below. 


Note. The Operation Of The Manually-operated Pre-select- 
iv e Stage Switchboard (Figs. 502A and 502C) is, briefly, as follows: 
The bearing casting, B, Fig. 502B, is rigidly fastened to the shaft S, so 
that operation of the master lever (M, Fig. 502A) rotates the bearing 



Fig. 502A.—Four switch levers of a manually-operated pre-selective stage switch¬ 
board. The pre-set lever ( L, Fig. 502B) is shown in the four different positions. 
(Mutual Electric & Machine Co., Detroit, Mich.) 

casting of each magazine switch on the shaft, whereby the switch may 
be opened, closed or not moved depending on the position of the pre¬ 
set lever. The magazine switch handle is connected by a link to the 
switch by an arrangement similar to that shown in Fig. 504. The pre¬ 
set lever, L, Fig. 502B, has four positions: (1) Off. (2) Positive. (3) 
On. (4) Independent. When the pre-set lever L, is in the Off position 
(A, Fig. 502A), operating the master lever downward will open switch 
A, but operating it upward will not close A. With the pre-set lever in 
the On position ( B , Fig. 502A) operating the master lever upward will 
close switch B, but operating it downward will not open B. With the 
pre-set lever in the Pos (positive) position (C, Fig. 502A), operating 
the master lever downward will open C and operating it upward will 
close C. If the pre-set lever is in the Ind (independent) position (Z), 





384 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 



Magazine 
Switch 
Handle 


Spring 

Latch- 


•■hearing —_ 
Casting 



F-Front Elevation 


Fig. 502B.—Magazine^switch lever mechanism of a manually-operated pre-selective 
f[stage switchboard. (Mutual Electric cfc Machine Co., Detroit, Mich.) 


c c c 



1-Off-Turning ~S” 
Jhrouojh Angle 
'’VTAnol Back, 
Carr ies"H”Over 
To"05” Opens 
Switch, And 
Leaves'l-f There, 
Leaving Switch 
Open. 


F-Positive- M 
Turning "S" 
Through Angle 
'h"Anol Back 
Carries"'H "Over 
To"OS"And Then 
Back To'CS” 
Opening And 
Closing Switch 
And Leaving 
It Closed 


H-On-Turning S” 
Through Angle 
"M”And Back,"b” 
Engage s"h” And 
Carries It Back, 
Closing Switch 
And Leaving 
It Closed 


17-Independent- 
Turning's” 
Does Hot 
Move"H” 


Fig. 502C.—The four “ pre-setting” positions of the manually-operated pre-selective 
switchboard. (In effect, H is connected, by a link, to the switch about as shown in 
Fig. 504. With the pre-set lever in the off position as shown at I, further operation of 
S by the master lever (M, Fig. 502A) will not move the switch after it is closed. Simi¬ 
larly, with the pre-set lever in the on position (III) after the switch is closed by S, 
further operation of S will not open the switch.) 





















































































Sec. 427] 


THEATRE CIRCUITS 


385 


Fig. 502A), switch D cannot be opened or closed by operating M. The 
switchboard operator pre-sets for a scene as follows: The pre-set levers 
of those magazine switches that control the lamp groups which are to 
remain either lighted or extinguished for the next scene are placed in the 
Ind position. The pre-set levers of those magazine switches that con¬ 
trol lamp-groups which are not then lighted but which are to be lighted 
for the next scene are set in the On position. The pre-set levers of those 
magazine switches that control lamp-groups which are then lighted but 
which are to be extinguished for the next scene are set in the Off posi¬ 
tion. Then, when the cue for the next scene is received, the switchboard 
operator moves the master lever downward and then upward. This 
provides, almost instantaneously, the desired lighting effect for that 
scene. 


427. Some Of The Various Types Of Switches Which Are 
Employed In Dead-front Manually Operated Stage Switch¬ 
boards are shown in Figs. 503, 504, 505 and 506. The 


Hancde- 

,-Connecting Lugs 
Stop^ 


<-■5late 
Base 

- - Snitch 

T 




Connecting 


'Connecting Link 

''Quick-Break 

Mechanism 

-*■Fuse Clips 


n 


a. 

jO • , r g 

.x[6 

A 

:4J 

m 

y 


BBsHpE. 


: ?f 

rM 

}l 

ill •'. 



Jl 

T 

Fuses- 



a 

3 •' ° 


1 1 

1 


Hanclle- 


■Cross 

bar 


Circuit Name 
Plate - N 



111-Front View Of 
Handle 


I-Side View Of Switch -- 

And Handle Switch 

Fig. 503.—Manually-operated switch for a dead-front stage switchboard. ( Metropoli¬ 
tan Electric Mfa. Co.) 


switches shown in Figs. 503 and 506 are provided with a quick- 
break mechanism. The switch illustrated in Figs. 504 and 
505 has a double break-jaw and no hinge-jaw. The fuses, 
which are carried on the back of the switch form a part of the 
switch blades. 

Note.—The Rating Of The Magazine Switches On A Manually- 
operated Stage Switchboard is seldom less than 60 amp. Switches 
which have a rating of 100 amp. are frequently used, even though 
the connected load requires a current much smaller than 100 amp. 
This is to insure mechanical strength and ruggedness. However, 
25 





























































386 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


lb' Busbar 



Slate .> 


•Shaft 


Jaws 


: .blades 


Fuses- 

To Magazine 
PaneZ 


-Connecting 

Link 


Fig. 504. —Showing arrangement of the switch and handle for a dead-front manually- 
operated switchboard. ( Mutual Electric & Machine Co.) 


Block Of 
Insulating 
Materia!-* 



Quick-Break 
] Mechanism'S 


■--■Conduit 


Copper Busbar 

Fig. 505. 


Strap 



Switch Blade 
I (Open) 

.-Slate 

JLJgJ 

witch 
Blade 
(Closed) 


Connect in a 
Link . 


Conduit . 

Outlet" 

Fitting 


Steel 

Angle Frame 


Fig. 506. 


Fig. 505.—Closed position of double-pole magazine switch for a dead-front, 
manually-operated switchboard. ( Mutual Electric & Machine Co.) 

Fig. 506.—Showing quick-break switch for manually-operated dead-front stage 
switchboard. ( Pringle Electrical Mfy. Co.) 































































































































































Sec. 428] 


THEATRE CIRCUITS 


387 


they may be fused (Sec. 449) with as small-sized fuses as the magazine 
sub-feeders will permit (Sec. 169). 

428. One Principal Type Of Remote-control Stage Switch¬ 
board is known as The Major Pre-selection System Of Remote 
Control. It was invented by R. E. Major of the Major Equip¬ 
ment Co., 2518 Cullom Ave., Chicago, Ill. It is manufactured 
and sold by the Frank Adam Electric Co., St. Louis, Mo. 
The advantages of this system of theatre lighting-control, 
the description of the various elements and the circuits of 
this switchboard are discussed in the following sections. 

429. The Advantages Of The Major Pre-selection Control 
System are: (1) Pre-selective features and maximum flexibility 
of control which can not he obtained with the manual control 
system are provided. (2) Simple to operate. (3) An extremely 
safe apparatus as regards both personal injury and fire hazards. 

(4) It is made up of a number of standardized unit elements. 

(5) It occupies a minimum of stage-floor space. How the above¬ 
advantages are obtained will be understood by a study of the 
subsequent material. 

430. By “Pre-selective” Control is meant the control 
where by the stage electrician can select in advance the lamp- 
groups, which he desires to have lighted or extinguished simul¬ 
taneously for the next lighting effect. This he may do 
without interfering with the lighting effect then in use. The 
pilot switches which control these groups, having been “set¬ 
up,” he can instantly light all of them together by operat¬ 
ing the master pilot switch. The pre-selective control is 
obtained by a certain method of interconnection of the pilot 
switches with the remote control switches. This general 
method of interconnection is described in following sections. 

Example.—The Pre-selective Features And The Flexibility 
Of Control Which Is Provided By The Major System is illustrated 
by the following simple lighting-effect changes. The stage is assumed to 
be dark; that is, no stage lamps are lighted. At a certain signal the white 
foots, white border No. 2 and red border No. 1 are to be lighted. The 
switchboard operator places, in advance of the signal, the proper pilot- 
switch handles in the set-up position. Then, when the signal is received, 
he gives the proper master pilot switch a light tap with his hand. This 
simultaneously lights all of the lamps mentioned above. The second 
lighting effect is to be provided by the white foots, the red prosceniums 


388 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


and the blue border No. 4. He again places, in advance, the proper pilot 
switches in the set-up position. This he may do without disturbing 
the lighting-effect then in use. Then when he receives the signal for the 
second lighting effect, he gives the two master pilot-switch handles a light 
tap with his hand; whereupon the lighting-effect which is provided by 
t he white foots, white border No. 2, and red border No. 1 is instantly and 


Dimmers 
In Rear 
Of Pilot 
Board 


Stage Master 
Pilot Switch- 



Tumbler 

Switches 

Controlling 

Constant 

Circuits 

Dimmer 

Color- 

Master 

Handle 


'"House 
Master 
Pilot 
Switch 

Grand- 

Master 

Slow 

"Motion 

Dimmer 

Drive 



'Channel 

Support 


Three-Wire >/ 
Stage Cable-''' 

~a M Sub-Master 

Phot 5witrV fer Pi,0f 5wifch Auxiliary Portable 

Pt/Ot Switch Master Switch 

Sheet-Steel Case 


Fig. 507. —Major combination dimmer and pilot board. (Manufactured by The Frank 

Adam Electric Co.) 


simultaneously changed to that which is provided by the white foots, 
red prosceniums and blue border No. 4. How the operating circuits 
are controlled, by the pilot and the remote-controlled switches, and the 
circuit arrangements which are necessary to produce these lighting 
changes are explained and shown in Sec. 435. 

431. The Major Pre-selection System Of Remote Control 
Comprises Two Essential Elements: (1) A pilot board (Sec. 





































































































































Sec. 431] 


THEATRE CIRCUITS 


389 


416 and Fig. 507) which consists of the desired number of 
pilot switches (Sec. 416), and which is located (Fig. 531) on 
the stage. (2) A remote board (Sec. 416 and Fig. 508) which 



Fig. 508. —Major remote board installed in Sheridan Park Theatre, New York City. 

(Manufactured by Frank Adam Electric Co.) 


is usually located (Fig. 530) below the stage or elsewhere, 
preferably near the load center. The individual pilot switches 
(Sec. 432) on the pilot board serve the same purpose as do the 



Fig. 509.—Diagrammatic arrangement of a pilot switch, a remote controlled switch and 
the magazine circuit which is controlled thereby. 

momentary-contact switches (Div. 8) which are used to 
control any remote-controlled switch. The remote-controlled 
switches (Sec. 323) on the remote board are, in reality, merely 




















































































390 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


remote-controlled magazine switches (Sec. 416). That is, 
when a pilot switch ( P , Fig. 509) is operated, the control 
circuit of the remote-controlled switch, R, is closed. This 
either opens or closes the remote-controlled switch (Sec. 323), 
thereby lighting or extinguishing those lamps which are 
connected to the magazine panel, M, controlled by that switch. 

Note.—The Major Pre-selection System Of Remote-controlled 
Stage Switchboard will hereinafter be referred to as the Major System. 

Note.— In The Major System, The Dimmers May Be Mounted In 
The Rear Of Or On Top Of The Pilot Board. When the dimmers 
are mounted in rear of the pilot board (Fig. 507), they are so arranged 
that each dimmer handle projects through the front side of the board 
directly below the pilot-switch handle that controls the circuit which 
contains that dimmer. When the dimmers are mounted above the pilot 
board, the arrangement is similar to that indicated in Fig. 502 for a 
manually-operated board. 

Note.—The Remote-controlled Switch Which Is Used In Con¬ 
nection With The Major System is shown in Fig. 394. Its operation 
is described in Sec. 323. 

432. The Major Pilot Switch Unit (Figs. 510 and 511) 
consists of two single-pole double-throw switches ( A , and B, 
Fig. 511-/7) mounted on a thermoplax (moulded-asbestos 
compound) base as shown in Fig. 510. Its operation is 
explained below. 

Explanation. —Both switches (A and B, Fig. 511) are identical 
in construction. Each switch is held in the open position by a spring 
(S, Fig. 511-7). When either handle, H is pressed downward, as shown 
in Fig. 510, the contact block, D, touches the laminated-copper contact, 
E. This is called the momentary position (Fig. 512-7) because as soon 
as the pressure on the handle is removed, the spring ( S , Fig. 511-7) 
causes the switch to return to the open position. When either handle 
is pulled upward as shown at HB in Fig. 510, the blade ( F , Fig. 511) 
contacts with the jaw, J. The friction between the jaw and the blade 
holds the switch in this position until the switch handle is pushed down¬ 
ward by hand. This is called the set-up position (Fig. 512-77). 

The thermoplax base is provided with an indicating lamp, (P, Fig. 
511-77). The indicating-lamp terminals ( M and N) are connected to 
the lamp-receptacle as indicated at P, Fig. 511-777. The lamp, P, 
is so connected (Sec. 443) that it is illuminated when the lamp-group 
which is controlled by the switch on which the lamp is mounted is lighted, 
and extinguished when the lamp-group is extinguished. 

When several pilot-switch units (Fig. 510) are mounted on the support¬ 
ing frame, as in Fig. 507, the metal guard or front plate (M, Fig. 510) of 


Sec. 432] 


THEATRE CIRCUITS 


391 


each switch protects all live parts of the board from contact from the 
front. Thus, the pilot board is (Code Rule 38c) a dead-front board. 



Opening Switch-'" 
In Momentary 
Contact Position' 


Closing Switch 
In Set-Up 
Position . 


CohtactX. 
i Contact 
lock 


Handle 

’aw For 
Set-Up 
Position 


Thermop/ax 

<--Base 



Pilot Lamp- 
Handle, H\ 


I: y --Blade,? 


-■Jaw, J 



Fig. 510. —Major pilot switch unit. 



Fig. 511.—The Major pilot switch. (Manufactured by Frank Adam Electric Co.) 


A wire (IF, Fig. 511 -III) provides a permanent electrical connection 
between the laminated copper contact of switch A and that of switch B. 
















































































































392 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


Thus, when switch A is closed to the momentary position, an electrical 
connection is made between terminals L and C (Fig. 511-/). When 
switch A is closed to the set-up position, electrical connection is made 
between terminals C and 1. When switch B is closed to the momentary 
position, electrical connection is made between terminals L and 0. 
When B is closed to the set-up position, electrical connection is made 
between terminals 0 and 2. 

Note.—The Symbolical Wiring Diagram Of A Pilot Switch is 
shown in Fig. 512. 


5et-Up Position- 


fl 


I-Pi lot Switch 
Symbol, Both 
Switches In 
Neutral Or Off 
Position 


Momentary Position 

►f/A 

K' ' 
0 
L -O 

0-L 

°l 



Switch 

Symbol, 

Switches 

Closed 


N 


m-piiot 

Switch 

Wiring 

Diagram 



Two Dimmer Plates 
Mounted On One 
Unit- -, _ 

rji] 

Dimmer 
Plate—> 


r J r 




H-Remote 
Controlled- 
Switch Wiring 
Diagram 


Y- Dimmer 
Symbols 


Fia. 512.—Wiring diagrams and symbols of pilot switch, and wiring diagram of 
remote-controlled switch and dimmers for the Major system of remote control. (For 
remote-controlled switch symbol, see Fig. 513.) 


433. The Circuit Diagram Of The Major System For A 
Single Lamp-group is shown in Fig. 509. Switch A (Figs. 509 
and 511) is called the closing switch. This is because the con¬ 
nections are so made that it operates to close the remote- 
controlled switch, R. Switch B (Figs. 509 and 511) is called 
the opening switch. This is because it operates to open the 
remote-controlled switch. When switch A (Fig. 509) is 
closed to the momentary position (dotted position) the closing 
coil of R is energized (see Sec. 323) and R closes. This lights 
the lamps. When B is closed to the momentary position, the 
opening, coil of R is energized, and R opens. This extinguishes 
the lamps. The circuits may be traced out by referring to 
Fig. 509. The pilot switches are so mounted on the pilot board 
and are so connected to the remote-controlled switches that 
the upper row of handles (Fig. 507) in any horizontal row 
of pilot switches contains the opening-switch handles. 
Consequently the lower row of handles in any horizontal row 
contains the closing-switch handles. All opening pilot switch 
handles are painted black. All closing pilot switch handles 
are painted to correspond to the color of the lamps which 
they control, as red, white or blue. 

























Sec. 434] 


THEATRE CIRCUITS 


393 


Explanation. —The elementary arrangement shown in Fig. 509, 
which consists of only one pilot switch, one remote-controlled switch and 
one lamp-group, is never used in the Major system. However, by a 
careful study of the circuits shown therein, and of the operation of the 
pilot switch (Sec. 432) the following descriptions of the preselective 
features and of the flexibility of control which are provided by this 
system will be readily understood. 

434. One Pilot Switch May Be So Connected That It Will 
Control Two Or More Other Pilot Switches as indicated in 
Figs. 513 and 514. Switch No. 1 (Figs. 513 and 514) is, as 
explained below, so connected that it will control the group of 



Fig. 513.—One pilot switch so connected as to control two, or more; other pilot 
switches. (The set-up and the current path is shown for lighting lamp-groups L 
and M.) 

individual pilot switches Nos. 2, 3 and 4. Hence, it is (Sec. 
416) a sub-master pilot switch. This arrangement is nearly 
always employed on major theatre switchboards. Also such 
an arrangement of connections is, when there are only a few 
lamp-groups in the house, sometimes used to control the 
house lights. Then, switch No. 1 (Figs. 513 and 514) is 
called the house master pilot switch , or the house main. 

Explanation. —Note that the connections which are shown in Fig. 513 
are identical to those which are shown in Fig. 514. The individual pilot 
switches, Nos. 2, 3 and 4 (Figs. 513 and 514), are so connected (Sec. 431) 
as to control, respectively, remote-controlled switches Nos. 2, 3 and 4. 
In Fig. 513, the closing switches, A, of individual pilot switches Nos. 2 
















































































394 


LIGHTING CIRCUITS AND SWITCHES 


[Diy. 9 


find 4 are placed in the set-up position. Then, by operating the closing 
switch of pilot switch No. 1 to the momentary position, remote-controlled 
switches Nos. 2 and 4 are simultaneously closed, and lamp-groups L and 
M are lighted thereby. The current-paths through the control wires 
and through the closing coils of the remote-controlled switches are, for 
this operation, indicated by the light arrows. The current-paths 
t hrough the lamp-groups are indicated by the heavy arrows. The closing 
switches, A, may now be returned to the open position and the lighting 
effect will not be changed thereby. 

How lamp-groups L and M may be simultaneous^ extinguished 
by pilot switch No. 1 will now be explained. Place the opening switches, 
B, of individual pilot switches Nos. 2 and 4 in the set-up position. Then 

. Pilot Switch Connected To Control Pilot Switch 



Fig. 514. One pilot switch so connected as to control two or more other pilot 
switches. (The set-up and the indicated current-path is shown for extinguishing lamp- 
groups L and M.) 

operate the closing handle, B ) of switch No. 1 to the momentary position. 
Current will then flow through the control wires and through the opening 
coils of remote-controlled switches Nos. 2 and 4, as indicated by the 
arrows. When the current flows through the opening coils, the switches 
aie (Sec. 323) opened, and the lamp-groups, L and M, are extinguished. 

When a pilot switch is closed to the momentarj'' position ( A , switch 
No. 1, Fig. 513, and B, switch No. 1, Fig. 514), it is only necessary to 
hold it in this position for an instant. Then the hand should be removed 
from the handle, whereupon the switch will (Sec. 432) be returned to the 
open position. However, since the coils of the remote-controlled switches 
are (Sec. 323) designed for continuous duty, no harm other than a waste 
of energy will result if a pilot switch is held closed to the momentary 
position for an indefinite length of time. 

















































































Sec. 435] 


THEATRE CIRCUITS 


395 


435. A Circuit Diagram Which Illustrates The Major 
System is shown in Figs. 515,516 and 516A. Theoretically, any 
number of individual pilot switches—and consequently the 
corresponding number of remote-controlled switches—may be 
controlled by one sub-master pilot switch. Also, theoreti¬ 
cally, any number of submaster pilot switches may be 


■Pilot Fuses And bus 


Master 

Pi/of 

Switch 


''Push- 

button 

'Momentary- 

Contact 

Snap- 

Switch 



Sub-Master-- 
Pilot 
Switches 

Remote TorrFroiled Twitches. 

£ 

From General ~ A 

.Lighting Cabinet >' 


Closing CoH- 


To Lamp-Croup 
Through Dimmers 
And Magazine 
Panel 


Remote Board 


Fig. 515 .—Simplified circuit diagram of the Major system of remote-controlled 
stage switchboard for an alternating-current system when not more than six individual 
pilot switches are controlled by one sub-master pilot switch, or for a direct-current 
system when not more than twelve individual pilot switches are controlled by one sub¬ 
master pilot switch. 


controlled by one master pilot switch. However, practical 
considerations (Sec. 436) limit these numbers. The circuits 
shown in Figs. 515 and 516, and the control which is afforded 
thereby (see explanation below) typify the Major system. 















































































































































































396 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


Explanation. —The following explanation refers specifically to Fig. 
515. The circuits are shown for one master pilot switch, No. 1, two 
sub-master pilot switches, Nos. 2 and 3, and six individual pilot switches. 
The six individual pilot switches, Nos. 5, 6, 7, 9, 10 and 11, control 
respectively the six remote-controlled switches, Nos. 5, 6, 7, 9, 10 and 
11. The two sub-master pilot switches, Nos. 2 and 3, control, respectively 
the individual pilot switches Nos. 5, 6, 7, and 9. 10, 11. The master pilot 
switch, No. 1, controls the two sub-master pilot switches, Nos. 2 and 3. 
Each remote-controlled switch, Nos. 5 to 12, inclusive, controls (Sec. 431 



Fig. 516.—Connection diagram of control circuit used in the Major system for master, 
sub-master and individual pilot switches. (Not more than twelve individual pilot 
switches, when direct current; nor more than six individual pilot switches, when alter¬ 
nating current, to be controlled by one sub-master pilot switch. 


and Fig. 509) one lamp-group. Thus, when a remote-controlled switch is 
opened or closed, that lamp group which is controlled by it is extinguished 
or lighted. The example which follows illustrates the simplicity of the 
operation of this pre-sclective system. 









































































































Sec. 435] 


THEATRE CIRCUITS 


397 


Example. Assume that no stage lamps are lighted, that is, that the 
stage is black out/’ Also assume that at a certain signal, the white 
foots, the white border No. 2 and the red border No. 1 must be lighted. 

Note that each pilot switch is provided with a nameplate, Fig. 510, 
which bears the name of the circuit that it controls. Further assume 
that the above-named lamp-groups are controlled respectively by the 
remote-controlled switches Nos. 5, 7 and 10, which are (see diagram, 
Fig. 515) in turn controlled, respectively, by individual pilot switches 
Nos. 5, 7 and 10. To set up the board for the desired change, the switch¬ 
board operator places the closing pilot switches (Sec. 433) Nos. 5, 7, 2, 
10 and 3 in the set-up position. Then, when he receives the signal, he 
shifts the closing handle of the master pilot switch, No. 1, to the momen- 



Fig. 516A.—Circuit diagram of a complete Major system of stage-switchboard control. 

{Frank Adam Electric Co.) 


tary position (shown in dotted lines) and holds it there for a moment only. 
Whereupon, those lamp-groups which are controlled by remote-controlled 
switches Nos. 5, 7 and 10 are lighted simultaneously. The path, through 
the control circuits, of the current which operates remote-control switches 
5, 7, and 10, as explained above, is indicated by the arrows. 

After master pilot switch No. 1 has been closed for an instant to the 
momentary position the remote-controlled switches, Nos. 5, 7 and 10, are 
closed and locked closed (Sec. 323). They will not open until the opening 
coils are energized. Consequently, the closing-pilot switches, Nos. 2, 3, 
5, 7 and 10 may now be returned to the open position and the lights which 
are controlled by them will not be extinguished. This enables the switch¬ 
board operator to pre-select and “set-up” in advance (Sec. 429) for the 
next lighting effect. Then when he receives the signal for this_next 



























































































































































LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


398 

lighting effect, he can produce it instantly and simultaneously by the 
operation of the master-switch handles. 

Assume that the next lighting effect requires the light from those lamp- 
groups which are controlled by remote-switches Nos. 5, 6 and 11. This 
is “set up” as follows: (1) Return all of the opening pilot switches to the 
neutral position. (2) Place the closing pilot switches Nos. 5, 6, 2, 11, and 
3 in the set-up position. (3) Place the opening pilot switches Nos. 7, 2, 10 
and 3 in the set up position. Now, when the signal is received for this 
second lighting effect, both the opening and closing switches of the master 
pilot switch, No. 1, are simultaneously operated to the momentary 
position and held there for an instant. This extinguishes Nos. 7 and 10, 
and lights Nos. 6 and 11, and permits No. 5 to remain lighted. The 
result is that the lighting effect of Nos. 5, 7, and 10, is instantly and 
simultaneously changed to that of Nos. 5, 6, and 11. The current path 
(arrows not shown) in the control circuit for this lighting change may be 
traced out by referring to Fig. 515. 

It will be evident from the above that the lighting effect of any com¬ 
bination of any number of lamp-groups may be simultaneously changed 
to any other desired combination of any number of lamp-groups. Fur¬ 
thermore, any lamp-group may, by operating its individual pilot switch, 
be lighted or extinguished at any time without interferring with any other 
lamp-group. 

436. A Single-pole Sub-master Remote-controlled Switch 
Is Provided On The Major Remote Board (Fig. 517) for each 
sub-master pilot switch when: (1) One sub-master pilot switch 
controls more than six individual pilot switches for an alternating- 
current system. (2) One sub-master pilot switch controls more 
than twelve individual pilot switches for a direct-current system. 
The connections are so arranged that the control which is 
provided is exactly the same as that explained under Sec. 435 
in connection with Fig. 515. The reason for using these single¬ 
pole remote-controlled switches is, as explained below, to 
prevent the possibility of having to break an excessively heavy 
current with the master or sub-master pilot switches. 

Explanation. —Assume that more than six, say seven, individual pilot 
switches are controlled by one sub-master pilot switch. Assume, also 
that the system is to be used on alternating-current and' that the 
general scheme of connections is as shown in Fig. 515. Then, if it is 
desired to simultaneously light all of the lamps controlled by these seven 
individual pilot switches, each individual closing-pilot switch would be 
placed in the set-up position. The lamps would then be lighted by 
operating the sub-master closing-pilot switch to the momentary position. 
The alternating current which is required to close one Major remote- 


Sec. 436 ] 


THEATRE CIRCUITS 


399 


controlled switch is (Sec. 323) about 7.7 amp. Then, the sub-master 
pilot switch would, when operated to the momentary position under the 
conditions outlined above, carry about 7 X 7.7 = 53.9 amp. Further¬ 
more if all the lamps which are controlled by two sub-master switches 
were to be simultaneously lighted by means of the master pilot switch, 
the current which would pass through the master pilot switch would be: 
2 X 53.9 = 107.8 amp. Such a heavy control current would, in addition 
to injurying the master or the sub-master pilot switches, require larger 
pilot fuses (Sec. 450) and, consequently, larger wires in the pilot-board 
feeder circuits. 

To eliminate the objections which are outlined above, a single-pole 
remote-controlled switch (No. 2, Fig. 517) is connected into the circuit 



Fig. 517.—Simplified circuit diagram of the Major system of remote-controlled 
stage switchboard for an alternating-current system when more than six individual 
pilot switches are controlled by one sub-master switch, or for a direct-current system 
when more than twelve individual pilot switches are controlled by one sub-master pilot 
switch. 

as indicated. As shown in Fig. 518, instead of connecting terminal C of 
the sub-master pilot switch to terminal 1 of the individual pilot switches, 
as in Fig. 516, it—terminal C — is connected to one side of the closing coil 
of the single-pole sub-master remote-controlled switch (No. 2, Fig. 517, 
and A, Fig. 518). The other side of the closing coil of switch No. 2, 
Fig. 517 and A, Fig. 518, is connected to the grounded side of the 
line. Switch A , Fig. 518, has no opening coil. It is opened by gravity and 
a spring (Sec. 323) when the control circuit through the closing coil is 
broken. One of the load-circuit wires, ( W , Fig. 518, Sec. 316) of switch A 
is connected to the line or bus at G, and the other side, V , is connected to 
terminals 1—set-up terminals—of the individual closing pilot switches 
(switches 3, 4 and etc.) that are controlled by the sub-master pilot switch, 
No. 2, which controls A. Thus, when A (Fig. 518) is closed, current 
flows, as indicated by the arrows, (Fig. 517 and 518) to the set-up termi- 


















































































400 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 0 


nals—terminals 1—of the individual pilot switches. Therefore, when 
the individual closing pilot switches are placed in the set-up position, 
current will flow through the closing coils of the corresponding remote- 
controlled switches. Consequently, instead of the circuit which carries 
this heavy current being broken by the master or sub-master pilot 
switches, it is made and broken by the single-pole remote-controlled 
switch. 


Pilot-Board 



Fig. 518—Diagram of control circuit of the Major system for master, sub-master and 
individual pilot switches. (More than twelve individual pilot switches, when direct 
current; or more than six individual pilot switches, when alternating current, to be 
controlled by one sub-master pilot switch. Frank Adam Electric Co.) 

Since the current (Sec. 323) required to open the remote-controlled 
magazine switches is small about 2.1 amp., alternating-current—a 
i emote-controlled sub-master switch is not usually required in the opening 
circuit. 

437. The Switches On A Major Pilot Board May Be Classi¬ 
fied as: (1) The stage pilot switches ; which control the stage 



























































































































Sec. 438 ] 


THEATRE CIRCUITS 


401 


lights. (2) The house pilot switches; which control the house 
lights. (3) The constant-circuit snap switches; which control 
the work lights. Each classification is briefly described in 
the following sections (see also the specification, Sec. 452, 
Clauses, 27 and 28). 

438. The Stage Pilot Switches Are Usually So Connected 

that: (1) Each stage magazine circuit is provided with one 
individual pilot switch . (2) Each lamp-color is provided with 

one sub-master pilot switch. (3) One master switch controls 
all stage lights. Thus, a sub-master pilot switch is, in effect, 
a color-main switch (Sec. 416). And the master pilot switch 
for the stage lights is, in effect, the stage-main switch (Sec. 416) 
(see Sec. 452, Clause 26). 

Note.—The House Pilot Switches Are, In General, So Con¬ 
nected that the same arrangement of master, sub-master and individual 
pilot switches is provided with respect to the house as that which is 
explained above for the stage. However, where the number of lamp- 
groups for the house lights does not exceed 10 or 12, the sub-master pilot 
switches for house lights is sometimes omitted. In such cases, only a 
master pilot switch is provided for the house lights. It is so wired 
(Fig. 538) that it will control all of the house lights (see Sec. 452, 
Clause 27). 

439. The Constant-circuit Snap Switches (Fig. 519) are 
usually single-pole, double-pole or three-way switches of the 


Work-Light Branch Circuit. 



Fig. 519.—Circuit diagrams of the constant-circuit work lights as used in the Major 

system. 

tumbler type. They are used to control the work lights (Sec. 
415). The reason these circuits are called constant circuits 
is because the work-light branch circuits (Fig. 519) are con- 
26 












































402 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


stantly connected to the bus-bars on the remote board; that is, 
they are not controlled by a remote-controlled switch as 
are the magazine circuits which feed the stage and house 
lights (see Sec. 452, Clause 28). 



440. A Polarity-type Distribution Panel (Fig. 520) is 
one wherein all of the branch-circuit connections of the same 
polarity are located adjacent to each other. Thus, in the 



Fig. 521. Showing method of connecting a section of the magazine panel (Major 
system) to the source of energy. Two-wire circuit to magazine panel. 

three-wire polarity-type panel (Fig. 520), wires 1, 1, 1, form 
one three-wire branch; wires 2, 2, 2, form another three- 
wire branch, and so on (see also Fig. 535). In the two-wire 


















































































Sec. 441] 


THEATRE CIRCUITS 


403 


polarity-type distribution panel ( M , Fig. 521), wires 1, 1, form 
one two-wire branch; wires 2, 2, form another two-wire 
branch, and so on. A polarity-type distribution panel does 
not usually require as much space as a panel (Fig. 547) of the 
ordinary type. This is because the clearance which is 
required between bare metal parts of the same polarity is not 
as great as that which is required between parts of opposite 
polarity (see Sec. 166). The magazine panels (M, Figs. 521 
and 522) as used in the Major system are of the polarity type. 

busbars On Remote board 

Fed From Generab 



Fig. 522.—Showing the method as used in the Major system of connecting a two- 
pole remote-controlled switch as a three-pole switch. Three-wire circuit to magazine 
panel. 

441. The Two Methods Of Connecting The Magazine 
Circuits To The Source Of Energy As Employed In The 
Major System are illustrated in Figs. 521 and 522. In Fig. 
521, a two-pole remote-controlled switch, R, is connected, one 
pole to the neutral bus and one pole to one outside bus. The 
pole, H, which is connected to the outside or “hot” bus of the 
three-wire grounded-neutral system connects to one bus of 
the magazine panel, M. The neutral side, N, connects through 
the dimmer, D, to the other bus of the magazine panel, M. 
When the current required by the lamps which are connected 
to one magazine panel is large, the connections are made as 
shown in Fig. 522. The two-pole, remote-controlled switch 
( R , Fig. 522) is then wired as a “three-pole” switch. The 
hot busbar on the magazine panel, M, is divided into two 
sections A and B. One section is connected, through one 























































404 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


pole of R, to one outside wire, and the other section is con¬ 
nected, through the other pole of R to the other outside wire. 
The lamp load which is to be controlled by R is divided into 
two parts which are as nearly equal as is practicable. One 
part is connected to A. The other part is connected to B. 
Then the two neutral busbars, C, are connected through the 
dimmers to the neutral bus on the remote board (see also 
Sec. 446 concerning dimmer connections). 

442. The Major Pilot Board Is Fed From The Busbars On 
The Remote Board (B , Fig. 523) by the pilot-board feeders, 
F, through the magazine-panel pilot-board busbar, P. At 



I-Direct Control II-Remote Control 

Fig. 523.—Circuit diagram showing how the pilot board is fed in the Major system. 

P, the circuit is divided into the fused pilot-board sub-feeders, 
W, which feed directly to the various pilot switches. (See Figs. 
516 and 518.) 

Note.—The Major Remote Control System May Be “Locked” 
by either one of two arrangements: (1) By opening the double-pole knife 
switch, S, Fig. 523-7. (2) By pressing the button of momentary contact 
switch M which opens the remote-controlled switch, R, Fig. 523-77. 
That is, such house or stage lamps as are desired may be lighted as 
explaned in Sec. 435. Then, by opening S or R (Fig. 523) no current can 
flow through the opening or closing coils of the remote-controlled magazine 
switches. Consequently, none of the stage or house lamps can then 
be lighted or extinguished. Thus, by providing a lock on S or M, the 
stage and house lamps may be “locked” when either lighted or extin¬ 
guished. Opening S or R also cuts the pilot board dead so that changes 




















































































Sec. 443 ] 


THEATRE CIRCUITS 


405 


or lepairs may be made with safety. Opening S or R does not in any 
way affect the constant circuits (Sec. 439). By connecting lamp I (Fig. 
o23-77) as shown, it will be lighted when switch R is closed, and extin¬ 
guished when R is open. Thus, it indicates whether the pilot board is 
“dead” or “alive.” It is usually mounted (7, Fig. 537) in the top 
trim of the pilot board. 

443. The Indicating Lamps On A Major Individual Pilot 
Switch are connected as illustrated in Fig. 524. When con¬ 
nected as shown, the indicating lamp of each individual pilot 
switch will be lighted when the lamps which are controlled 
by that individual pilot switch 
are lighted; and it will be ex¬ 
tinguished when the lamps 
which are controlled by that 
individual pilot switch are ex¬ 
tinguished. Thus, the switch¬ 
board operator may, by a 
glance at the pilot board, 
know just which stage and 
house lamps are lighted and 

which are not lighted The ^dicating lamp of a Major individual 
. ... . pilot switch is connected. 

indicating lamp will, when 

connected as shown, burn at full brilliancy, even though the 
lamps are dimmed by the dimmers. The positions of the 
dimmer handles, or a pointer which may be provided on 
the dimmer, indicate the brilliancy of the lamps which the 
dimmer controls. The master and sub-master pilot switches 
are not provided with indicating lamps. 

444. In The Major System All Of The Stage And House 
Lights May Be Controlled By A Momentary-contact Switch 
which is really an auxiliary master switch (Fig. 525). This 
momentary-contact switch may be stationary and mounted at 
any desired location in the theatre. Also, it may be portable 
(Fig. 507) so that control of the stage and house lights may be 
had from the most advantageous location (see explanation 
below). 

Explanation. —For the example which was explained under Sec. 435, 
in connection with Fig. 515, the set-up was made and the lamps were 
lighted by closing the closing-switch of the master pilot switch, No. 1, 


Separate Wire For Each Switch- 


Individual 
Pilot Switch 

IM do. 14? 

Wire -i 

N 




One Wire 
For All 
Switches 

'Indicating 

Lamp 


Sections Of Magazine Panel- 


Fig. 524.—Circuit diagram showing how 































406 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 0 


to the momentary position. This permitted the current to flow from L 
to C (Switch No. 1, Fig. 515). By operating a two-circuit momentary- 
contact switch which is connected to the master pilot switch, as shown in 
Fig. 525, the closing-switch of the master-pilot switch (Fig. 525) being 
previously placed in the set-up position, the same result may be obtained. 
That is, by closing the momentary contact switch, as shown at M, 
current will flow from L to C as indicated by the arrows. Thus, the 
lights may be lighted or extinguished by the momentary-contact switch of 
Fig. 525, just as they were lighted or extinguished by the master pilot 
switch of Fig. 515. 

The Frank Adam Electric Co. regularly equips all Major boards with 
a three-point receptacle (R, Figs. 516, 518 and Sec. 452, Clause 26) 
which is located (Fig. 507) in the side trim of the pilot board. About 
50 ft. of No. 14, three-conductor stage cable (IF, Fig. 525, and Fig. 507) 


Master-Pi lot-Switch Sub-Feeder -... 


_ 

.■Two-Circuit Momentary-Contact Switch 

Closing Switch-- 


pA; 


W 4 t Opening Switch-- 


■* J L, 

1> 

j 

F 

FT - 0 

MiL 1 


Vf- '■ ; ; 

•Control Wires Master Pilot Switch 

-ui: 


Fig. 525.—Showing the method, which is used in the Major system, of controlling 
the house and stage lamps by a momentary-contact push-button switch. (Frank Adam 
Electric Co.) 

is also furnished. A two-circuit momentary-contact switch is connected 
to one end of this cable, and a three-point plug is connected to the other 
end. By inserting the plug into the receptacle (Fig. 507), the stage and 
house lamps may be controlled from almost any location on the stage by 
the momentary contact switch, as explained above. In some scenes it is 
difficult for the switchboard operator to get the signal for a lighting change 
from his usual position at the stage switchboard. In such cases, he may 
place the proper switches in the set-up position, plug in the cable, and 
take the momentary-contact switch in his hand and go to a place where 
he can readily receive the signal. Or, if desirable, the momentary- 
contact switch may be temporarily mounted in the scenery, so that it 
can be operated by the actor in full view of the audience. Then, the 
switchboard operator merely places, in advance, the proper switches in 
the set-up position and the actor controls the lights. 

445. Theatre Dimmers Are Used To Dim The House And 
Stage Lights. A dimmer is merely a rheostat—a resistor of 
variable resistance (Fig. 526)—which is connected into the 
magazine sub-feeder that feeds the lamp-group to be dimmed. 
The dimmers are mounted in a group, called the dimmer bank , 
above the stage switchboard (Figs. 502 and 527), or in rear of 





















Sec. 446] 


77/ EA TRE Cl R C UITS 


407 


or on top of the pilot board (Sec. 431 and Fig. 507). Each 
dimmer unit is provided with an individual handle. Shafts 



which are equipped with master and grand-master handles 
(Figs. 507 and 527) for interlocking several dimmer units for 

V • 



Fig. 527. —Dimmer bank mounted above a dead-front, manually-operated, interlocking 
stage switchboard. (Mutual Electric & Machine Co.) 

simultaneous operation are also provided. Various methods 
of dimmer connections are discussed in the following sections. 

446. The Dimmers Must Be So Wired That They Are Dead 

when the switch which controls the circuit of which the dimmer 











































408 


LIGHTING CIRCUITS AND SWITCHES 


[Drv. 9 


forms a part is open. (Code Rule 38c, 2.) Compliance with 
this rule requires that the magazine switch (717, Fig. 526) be 
a double-pole switch. Or if the dimmer is connected into the 
grounded-neutral of a three-wire system, it may be connected 
as shown in Fig. 522. Although, when the switch, R, Fig. 522, 
is open the dimmer is not disconnected from the line, it is, since 
it is in the grounded side of the circuit, considered to be dead. 

447. The Maximum Wattage Rating Of A Single Dimmer 
Plate is about 3,000 watts. When the magazine circuits 
which are connected to one magazine-panel section have a 
connected load greater than 3,000 watts, two or more dimmer 
plates are mounted as one unit. Then this unit is controlled 
by one individual handle. The method of connecting two or 
more dimmer plates to dim a single lamp-group is discussed 
in the following section. 

448. The Correct Method Of Connecting A Multi-plate 
Dimmer Unit is shown in Fig. 528-7. The magazine panel 


Lamps-■ 

h> 

-Q- 


A-Wiring Diagram C-Circuit Diagram 

I-Correct Method Of Connection 



Fig. 528. —Showing correct and incorrect method of connecting multi-pole dimmer units. 


Dimmer P/ates - 


Magazine 

'a 


y. r 

Sub-Feeders. 

F- 

p 


I 

— 



—ri 

~v 

Magazine Pane!-'' 


.■lo Lamps... 

B 


Dimmer 

Plates 







A 


Sab-Feeders '-. 


Magazine 



bus-bar, B, should be divided into as many sections as there 
are dimmer plates in the dimmer unit for that lamp-group. 
Then one dimmer plate should be connected to each bus-bar 
section, as indicated in Fig. 528. The load on the branch 
circuits which are connected to any one dimmer plate should 
be made as nearly equal to the wattage rating of that dimmer 
plate as is practical. 

Note.— An Incorrect Method Of Dimmer Connections is shown 
in Fig. 528-77. When connected as shown, the dimmers will work as long 



















































Sec. 449] 


THE AT RE CIRCUITS 


409 


as each dimmer plate operates satisfactorily. However, if trouble 
develops on one dimmer plate and puts it out of service, the entire 
load will then be carried by the remaining serviceable plates of that 
unit. Such a load shift may cause the entire unit to burn out before the 
trouble can be remedied. 

449. The General Rule To Be Followed In Fusing Stage- 
switchboard Circuits is to place a fuse of the proper rating 
(Sec. 170) at every point where a change is made in the wire 
size. Compliance with this rule will, in general, require fuses 
in the stage-main, house-main, color-main, and magazine 
circuits; also in each branch circuit at the magazine panel. 
Since each the stage-main, house-main, color-main and maga¬ 
zine circuits are usually provided with switches, the fuses and 
switches should, when practical, be so arranged that the fuses 
in any circuit will be dead when the switch which controls 
that circuit is open. The above applies, in general, to all 
types of stage switchboards. See Figs. 492, 493, 495, 496, 
497, 499, 500, 502, 503, 504, 506, 508, 516, 518, 519, 522, 523, 
and 524. Some of the special fusing which is generally 
followed in the Major system is discussed in the following 
sections. 

450. The Method Of Fusing Which Is Employed In The 
Major System is discussed below. In addition to complying 
with the general fuse requirements which are mentioned in 
Sec. 449, the Major system contains certain features which 
provide a protection against complete failure due to fuse 
blowing. These features are described in the following notes. 
In the major system, the pilot-board fuses seldom if ever blow 
because the circuits which they protect are not normally 
subject to troubles or to derangement. 

Note.—The Method Of Fusing And Feeding The Major Pilot 
Board is shown in Figs. 515, 516, and 523-7. The pilot-board bus on the 
magazine panel is divided into two sections (P and P, Fig. 523). Each 
horizontal row of individual pilot switches as Nos. 5, 6, 7, and 9, 10, 11, 
Fig. 515, is fed (Fig. 516) through a separate fused conductor ( A , B, and 
C, Fig. 516), from the upper section of the bus, P. Each section of P 
is fed from the buses, B, Fig. 523-7, through the fuses, X and Y. Thus, 
if any or all of the fuses, A, B and C, Fig. 516, should blow, the pilot 
board may still be operated through the medium of the master and sub¬ 
master pilot switches. Also, if the fuse in E (Fig. 516) should blow, the 
pilot board is still operative through the sub-master or individual pilot 


I 


410 LIGHTING CIRCUITS ANI) SWITCHES [Div. 0 

switches. If any or all of the fuses in F, G, or H (Fig. 516) should blow, 
the board may be operated through the master and individual pilot 
switches. If all of the fuses on the lower section should blow (those in 
E, F, G, and II), the board may be operated by the individual pilot 
switches. If either of the main fuses (X or Y, Fig. 523) blow, the pilot 
board may be operated through the individual pilot switches or through 
the master and sub-master pilot switches. 

451. A Method Which Is Sometimes Employed In Wiring 
The Footlights is illustrated in Fig. 529. As shown, alternate 
lamps in the footlight trough are connected to the same 
magazine sub-feeders, and every fourth lamp is connected to 
the same branch circuit. Thus if one of the fuses, F , in the 
magazine sub-feeder, blows, one half of the lamps will be 



Fig. 529.—Showing method of connecting footlights to alternate circuits. (This 
shows the wiring for the lamps of only one color. Similar circuits are used for each of 
the three colors.) 

extinguished, but the illumination therefrom will be evenly 
emitted throughout the entire length of the trough. Also, 
if one of the branch-circuit fuses, B, should blow one fourth 
of the lamps will be extinguished, but the illumination from 
the remainder of the lamps will be evenly distributed. This 
method of wiring the more important stage circuits will some¬ 
times prevent having to stop the show during a scene. This 
method may also be employed for border and proscenium lights. 

452. The Specification For The Electric Wiring Of The 
Indiana Theatre, Terre Haute, Ind., is contained in the 
following pages. It may be considered as a typical specifica- 














































Sec. 452] 


THEATRE CIRCUITS 


411 


tion for the electric wiring of a modern theatre which is 
designed for both motion-picture and dramatic performances. 
John Eberson, Chicago, Ill., was the architect. The electrical 
specification was prepared with the cooperation of R. E. Major 
of the Major Equipment Co., of Chicago. The installation 
called for in this specification was made by The Pierce Electric 
Co., Chicago, Ill. Only a few minor changes in arrangement 
have been made by the author. 


412 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


INDEX 

TO 

SPECIFICATIONS FOR ELECTRIC WIRING 

Clause • Clause 

Number Number 


Scope of This Work. 2 

Material and Workmanship.. 3 

Inspection. 4 

Working Drawings. 5 

Electrical-energy Supply. 6 

Method of Wiring. 7 

Conduit. 8 

Grounding. 9 

Wire. 10 

Size of Wire. 11 

Outlets. 12 

Detail Location of Outlets.... 13 

Outlet Accessories. 14 

Fuses. 15 

Distribution of Wiring. 16 

Control of Circuits. 17 

Emergency and Exit Systems 18 
Branch Circuit Lighting Cabi¬ 
nets. 19 

Motors. 20 

Service Fusing Cabinets— 

Switchboards & Panels... 21 

Cabinet “A”. 22 

Cabinet “B”. 23 

Cabinet “C”. 24 

Metering... 25 

Cabinet “P”—Pilot board on 

the Stage. 26 

Schedule of Pilot, Magazine 
and Remote Switches and 

Dimmers. 27 

Tumbler Switches on Pilot 

Board a P”. 28 

Work Lights. 28 

Rigging Loft. 28 

Orchestra Lights. 28 

Dressing Rooms. 28 

Heater Outlet. 28 

Cleaners’ Outlet. 28 

Remote Board Panel “D”... . 29 


Schedule of Remote Switch 
Controls from Panel “D” 30 


Footlights. 30 

Proscenium Strips. 30 

Border Lights. 30 

Cradle Spots. 30 

Balcony Floods. 30 

Orchestra Spots... 30 

Stage Pockets. 30 

Side Wall Coves. 30 

Organ Grills. 30 


Plaques, Grills and Orioles 30 
Cabinet “G”—Front Door¬ 
man’s or Lobby Cabinet. 31 

Schedule of Controls—Cabi¬ 


net^”. 32 

Sign. 32 

Cabinet “E”—Emergency 

Cabinet... 33 

Schedule of Controls from 

Cabinet “E”. 34 

Aislelites. 34 

Cabinet “S”—Sign Cabinet. 35 
Schedule of Controls from 

Cabinet “S”. 36 

Cabinet “H” in Converter 

Room. 37 

Picture Booth. 38 

Cabinet “O”. 39 

Dimmers. 40 

Telephone System. 41 

Conduits for Public Phones... 42 

Dressing Room Calls. 43 

Stores, Offices, Shops and 

Store Rooms.• 44 

Cabinet “J”. 45 

Cabinet “K”. 46 

Cabinets and Switchboard 

Diagrams. 47 

Guarantee. 48 

























































Sec. 452] THEATRE CIRCUITS 413 

SPECIFICATIONS FOR ELECTRIC WIRING, INDIANA THE¬ 
ATRE, TERRE HAUTE, INDIANA 

1. GENERAL: The foregoing pages of General Conditions shall 
apply to this branch of the work. (These General Conditions are not 
printed in this book , Editor.) 

2. SCOPE OF THIS WORK: These specifications contemplate the 
furnishing of all materials and labor required for a complete and high 
grade installation of light and power wiring for this theatre building, 
including feeders, panel boards and switchboards, fuse blocks and fuses, 
conduits and wires for the distribution of the lighting and power outlets 
called for on plans (see pictures of plans, Figs. 530, 531, 532, 533 and 534) 
or mentioned in these specifications; also including all outlet boxes and 
outlet box covers, receptacles and plates, drop cords, lighting switches, 
motor switches, service switches, a Major Combination Pilot Board 
and Dimmer Bank, remote board, borders, foot lights, proscenium strips, 
exterior decorative illuminating wiring, picture machines, house tele¬ 
phones, conduits for public telephones, signal system, and all apparatus 
shown on plans and mentioned in these specifications to make this 
installation complete, from the service company’s feeder to the most 
remote outlet, all ready for the attachment of fixtures and the lamping 
up of the house. All of the above to be to the entire satisfaction of the 
supervising architects and owner and all as described in these 
specifications. 

This installation will not include the incandescent lighting fixtures; 
it will not include the furnishing of any motors shown on plans in con¬ 
nection with the ventilating and heating system or elevator service or 
vacuum cleaner. However, it shall include necessary labor and materials 
to connect the motors shown and described on plans and specifications in 
connection with the following branches of the work: 

Motors for plumbing system. 

Motors for heating and ventilating system. 

Motors for organ. 

It shall also include connecting up of moving picture machines, spot 
lights and other arcs which are to be furnished for picture booth by 
others. 

3. MATERIAL AND WORKMANSHIP: All materials furnished, 
and methods of installation of same, shall be in full accord with the latest 
and best modern electrical and mechanical engineering practices. 
Although these specifications are intended as electrical specifications, 
contractor shall install all work in the best mechanical manner. All 
material and apparatus used in this building shall conform in all respects 
with the rules and requirements of the Electrical Inspection Department 
of the City of Terre Haute, Indiana, and the rules and regulations en¬ 
forced in this city by the National Board of Fire Underwriters. 

4. INSPECTION: Contractor shall apply for a permit from the 
Electrical Inspection Department of the City of Terre Haute, before 


414 


LIGHTING CIRCUITS AND SWITCHES 


[Drv. 9 





STORE 
R00 M 1 


Up To Cabinets 


STORE ROOM 2 


Meter Board 


sow.jn 


Cab J 




STORE ROOM 3 


1 “Const 6 No t4 Wires 
* For Shops 3 And4 


STORE ROOM 4 


Telephone CoSJo R un 
Wires To TbisXPoint 


p: 3 No 14 Wires In fCond. 
\ To Shop 5 


3 No. 8 
Wires In 
rCond. 


Public Telephones 
Above- 




To Cab K 
On 7- Floor 


To Cab K 




BOILER 

ROOM 


To Cab. 
InShop 


FUEL 

ROOM 


Up To Public Telephone 
In Box Office 


STORE 


ROOMS 


s 2//?y/y///////^777. 


SO W. K! 

zzzzzz 


'hzzzzzzzzzzzz- 

Fig. . r )30.—Basement plan of Indiana Theatre, Terre Haute, Ind., showinj 
























































































































































































Sec. 452] 


THEATRE CIRCUITS 


415 



electrical wiring. (Pierce Electric Co.) (See Fig. 532 for electrical symbols.) 





























































































































































































































416 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 0 


60W r 
J7. 

/O'Cir Cab.: 

10 Sn ■' 


4-CmCab. ■•'eo-W'M 
4Sw. ■' jn (&> 



Sign On 
Canopy- 


Io|o 

o 

o 

o’ 

o 

o 

o 

olololo 

o 

o|o[o|o 

o 

ne 

a 

□ 


Qj 

□ 


□ 

a 

K - 

1 

lafb 

□ 

□ 

olateln 

a 

a 

D 

alalala 

o 

D 

Sh 

UnJ^Ia 

c* * - • ~ 

Mi 

Jo'lo 

o 

olololo 

0 

olololo 

9 

Olololo 

9 


lj ~:S-2 Controls 132 Lights O Around Edges, 8 Circuits 
, -5'3 •• 99 ” d Inside Canopy 6 » 

Sign Outlet • 3 No. 4 Wires In “Cond. 


Fig. 531.—First floor plan of Indiana Theatre, Terre Haute, Ind., showing 





































































































































































































































































Sec. 452] 


THEATRE CIRCUITS 


417 


>1 



» # # 

clectric_winng. 

27 


{Pierce Electric Co.) (For electrical symbols see Fig. 532.) 





































































































































418 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


77//////7 ZZZ&Z zg 



To Cabinet 0 -' 


Fia. 532.—Second floor and gridiron plan of Indiana Theatre, 







































































































































































































Sec. 452] 


THEATRE CIRCUITS 


419 




/ Conduit To Constant 
Bus On Magazine Panel- 



Floor Over 
Organ Boom. -' 

Junction Box- 


ELECTRICAL SYMBOLS 


D 

$ 

►a 

•a 

□ 


Outlet T 20 


2 

E18 Below 


Ceiling Or Trough Outlet 
Aisle Outlet On Seat 
Bracket Outlet 
Base Outlet 
Floor Outlet 
c =Cj=‘ Fan Outlet 
tOj Power Outlet 
Qftc Drop Cord 

(S3 Telephone Outlet,Intercommunicating 
M Telephone Outlet, Public 

- Conduit, Overhead 

-Conduit, Under Floor 

- Signal Or Telephone Wiring 

— t — 1 Wire In Conduit 
—a — 2 Wires In Conduit 
-M— 4- Wires In Conduit 

■ sw. Wall Switch To 8 T19 Outlets f 

_ . In Attic/ 

Distribution Cabinet 

ES3 Junction Or Pull Box 
• Riser 

CPb Buzzer Outlet 

Aisle Outlet, Flush 


3-Way Switch 
On T6 



tZZZTTZZZZJL 




Up End For Future K3 Outlets 


fice 8 




Office 9 


Office 10 


a 




■ This Section Of Building Notin Electrical Contract 



?F =v2v/ /-'V/!F - 


Terre Haute, Ind., showing electric wiring. (Pierce Electric Co.) 








































































































































































































































420 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


.■SOW. EH 



J“Cond.,6Cir.ToCahG - --- -- 

72' 75'W. Outlets In Cornice Soffit On SI. - v 

Fig. 533.—Theatre and third floor plan of Indiana Theatre, Terre Haute, Ind., 
































































































































































































Sec. 452] 


THE A THE CIRCUITS 


421 


y Troughs} tt^ D n jX 


VIO'Andl-b'\30Amb.D4l\ m - T , 
Troughs,90-4Q-Y1' \ 30 Red - D44> ' r -°Mh. 


10 Amber D4l\ 
10Red -D44\ 


JUKed-D44r / J0 40 .„? hf {to Red -DU V 
Lights-: {30Blue -D47\ ; ' ^XlOBIue -D47 I 



Trough 

40-WLts. 


6AmbD4l ] 
6 Red-D 44 f 
6B!ue~D4l\ 






J0Amb.D4l\ 
nn An-w /' U 4 } TO Red D44 > 
90 tSZi^ fS 1 10 Blue -D41 1 


V10And7-6 Troughs 
rfs 


10'Trough i'/Si^d-DuV 




IE 


■Not In Electrical Contract- 


1 






V/////S 





showing electric wiring. (Pierce Electric Co.) (See Fig. 532 for electrical symbols.) 
















































































































422 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 




Y///////A 




6‘ Trough, 18 Lights 

See 3-Floor Plan- 






PROMEN A DA 


OPERATORS 

ROOM 


STORE 


.'■Y7 






STORAGE 




Sec 


Sec 


Sec 




/ 


□□ 

o □ 



rn 

nn 



□ □ 

CO 



nn 

nn 

r 

r 

on 

□□ 

4 


I*Longitudinal Section 

Fig. 534.—Longitudinal section of the Indiana Theatre, Terre Haute, Ind., 




































































































































































































































Sec. 452] 


THEATRE CIRCUITS 


423 


6 Orchestra 
Spots In Attic 
1,000-Yt. Each - • 


» * * # ■ ■» t'Cond To Mag. Panei 


i white -t>/J 

> A’ea' • 074 

> Blue - 



IS X-Ray 
Balustrade Lamps ■ 
See 3-Floor Plan '' 


2 10-Troughs 
30-Lights Each 
See 3- Floor Plan 


showing electric wiring. (Pierce Electric Co.) (See Hg. 532 for electric symbols.) 













































































































































































424 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


starting his work, notify that department when the work is ready for 
inspection and pay the final inspection fee on all incandescent lights, arc 
receptacles, signs and motors in the building. The certificate of inspec¬ 
tion shall not release the contractor from any defects in material, 
workmanship or design, should any develop within one year after final 
acceptance of the work herein specified. Contractor shall make all 
changes and repair any defects directed by the supervising architect, 
promptly, upon written notice, and without additional expense to the 
owner. 

5. WORKING DRAWINGS: The contractor must furnish a set of 
prints showing location of all outlets and special apparatus as men¬ 
tioned in the “Scope of the Work,” Clause 2, together with all wiring and 
conduit system showing sizes of same, and shall also make a drawing of 
the service and stage switchboards and the cabinets and panels, furnish¬ 
ing blue prints to the architect and owners for their approval, before 
starting the work. The detail shop drawing for all switchboards and 
panel boards must be submitted for the architect’s and owner’s approval. 
This is important and will be insisted upon. 

6. ELECTRICAL ENERGY SUPPLY: The system of electrical 
energy (current) supply for lighting system will be alternating current, 
3-wire, 110-220-volt, single-phase. The S3^stem of energy supply for 
power service will be alternating current, 440-volt, 2-phase, 4-wire. 
All feeders and mains for light will be on a 3-wire system. Branch cir¬ 
cuits in lighting system to various outlets to be run on 2-wire system. 

7. METHOD OF WIRING: All wiring in this building for light, arcs, 
motors, telephone and signal systems shall be run in iron conduit. All 
conduits throughout the entire installation shall be run concealed, except 
the runs on the stage. The conduit will be run in floor construction, 
attic space, partitions, and when run on brick walls where plaster occurs, 
contractor will cut the necessary chases in the brick in order to have the 
conduit covered with plaster where the plaster is put directly on the 
brick. Conduit runs for outside lights such as fire escape lights, shall be 
run inside of the building and come through to the outside of the building 
only at the outlets. It is intended that the conduits in the entire installa¬ 
tion shall form a complete raceway from the service board to each of the 
distributing centers and from the distributing centers to all the lighting 
and motor outlets. No wires are to be pulled into the conduits until the 
plastering has been done. 

8. CONDUIT: Conduit will be loricated iron pipe. Conduit will be 
carefully reamed to remove all burrs, and ends of pipe must butt into 
couplings. All conduits shall be run in long runs and not more than four 
quarter bends shall be made in one run of conduit. The necessary pull 
boxes or condulets can be inserted as desired in long runs of conduit to 
facilitate the pulling of wires. In no case shall a pull box be installed in 
an inaccessible location. Conduits when entering outlet boxes or 
cabinets shall be firmly fastened to same by lock nuts and bushings. 
Conduits in the entire installation shall be firmly fastened to the structure 
of the building. 


Sec. 452] 


THEATRE CIRCUITS 


425 


9. GROUNDING: The conduit shall be grounded in an approved 
manner in at least two places. 

10. W IRE: W ire used in this installation shall consist of tinned copper 
of 98 per cent, conductivity, to have a rubber insulation around the con¬ 
ductor of a thickness as given in the latest requirements of the City 
Electrical Inspection Department. The insulation is to have a double 
braid covering, for all wires larger than No. 8. Wire of the following 
companies will be acceptable for use in this work: G. E. Red Core , 
Simplex 11 ire & Cable Co ., American Steel & Wire Co., Standard Under¬ 
ground Cable Co. 

11. SIZE OF WIRE: The size of wire for distributing circuits for all 
purposes and main feeders shall be not less than the size given in the rule 
book of the Electrical Inspection Department, based on the entire load 
being in operation at one time. After obtaining the total current that 
each feeder carries, contractor shall refer to the rule book and select the 
size of wire required and then install the feeder consisting of the necessary 
number of the above size cables to constitute the entire feeder. On 
distributing circuits, more than one circuit may be run in one run of 
conduit, as described by the code rules. On borders, proscenium strips, 
foot-lights, cove lighting, and on all circuits which have a connected 
load in excess of 1,000 watts, No. 12 wire shall be used. 

12. OUTLETS: Each switch, light, receptacle and other outlet 
through the building shall be provided with an outlet box of heavy metal. 
Outlet boxes inside of building shall be of the knockout type, and shall 
be set in such a manner as to be flush with the finished plaster. All out¬ 
let boxes outside of the building shall be of the marine water-proof type 
Crouse-Hinds condulet with rubber gaskets. All outlet boxes shall have 
only the open holes which are necessary to accommodate the conduits 
entering same. Outlet boxes in all cases shall be firmly fastened to the 
structure of the building. 

13. DETAIL LOCATION OF OUTLETS: The location of the various 
outlets shown on the plans and mentioned in the specifications are only 
approximate and in order that all outlets shall come in proper relation to 
panels, pilasters, columns, etc., contractor shall study the details of these 
spaces, obtaining the necessary information from the ornamental plasterer 
and other contractors on the building, so as to make all the electrical 
work fit the work of the other contractors. In all cases, outlet boxes 
shall come in the center of the decorating panels, where same occur, so as 
to avoid any changing of outlets or decorating effects. In case any of 
the electrical contractor’s work is not properly placed to the approval of 
the architect, this contractor shall move same without additional expense 
to the owner. Ail ceiling and bracket outlets for the attachment of 
fixtures shall be equipped with fixture supports firmly fastened to the 
outlet boxes and the structure of the building. 

14. OUTLET ACCESSORIES: Where called for in these specifica¬ 
tions for equipping outlets with sockets, switches, etc., contractor shall 
use only association made devices. For drop cords, contractor shall 


426 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


furnish an Edison Key Socket, Loxon Lamp guard and reinforced cable, 
installing same in the outlet box cover having a bushed opening. Where 
flush switches are called for, contractor shall use G. E. No. 953 Tumbler. 
Where flush receptacles are called for, Cutler-Hammer Company’s 
No. 7711 shall be used. Furnish steel covered receptacles, P. & S. 
No. 443, for all light outlets except where fixtures or drop lights are 
specified. Some of the outlets have special equipments and are men¬ 
tioned further in these specifications. Lamps will be furnished by others, 
but lamping up shall be included in this contract. 

15. FUSES: The contractor shall furnish a complete set of fuses for all 
fuse openings in the building. Plug fuses shall be used for lighting- 
branch circuits of 30 amp. or less capacity, and cartridge fuses for all 
feeders, sub-feeders, mains and sub-mains and all circuits of over 30- 
amp. capacity. All National Electrical Code fuses shall be Buss or D & 
W non-refillable. 

16. DISTRIBUTION OF WIRING: The wire and conduit shall be 
run from cabinet to cabinet in the proper manner forming a chain of 
distribution, starting from the point of service entrance to the main 
distribution cabinet, then branching out from that point to all of the 
cabinets following. From the cabinets and switchboards, the wiring shall 
be run to the final points of distribution consisting of all light and power 
outlets, arc receptacles, sign outlets, etc. In distributing the wire to the 
lighting outlets from the above fuse cabinets, contractor shall group the 
outlets for such circuits in a consistent manner, placing not more than 
twelve (12) incandescent-lamp outlets, or 660 watts, on one branch 
circuit. For the borders, footlights and proscenium strips all trough 
and cove lighting, also canopy lighting, 1,320 watts may be placed on one 
branch circuit. Thirty-two aisle lights may be placed on one branch 
circuit. 

17. CONTROL OF CIRCUITS: The lights in general spaces through¬ 
out the building shall be controlled from the various fuse centers either 
by master switches or separate circuit switches as described later. In 
some of the rooms, lights are to be controlled by flush switches, which are 
to be placed so as to be visible from the light which is being operated. 
The location of the switches is as shown on plans. 

18. EMERGENCY AND EXIT SYSTEMS: The emergency system 
consists of all lights, indicated on the plans as “E,” (see illustrations) 
which are used to illuminate the house while the show is going on. The 
emergency lights in the auditorium, aisle lights, lights at each exit door, 
lights in foyer, corridors, stairways, courts and other portions of the 
theatre to which the public has access, shall be connected to a separate 
cabinet “E,” known as the emergency cabinet. This cabinet is to be fed 
by a separate feeder. There are several “service” circuits on the stage, 
in the basement and in the front portion of the building. These must be 
run so as to cut in ahead of all main switches on the various cabinets and 
to draw current through proper fuses in a manner that will allow these 


Sec. 452] 


THEATRE CIRCUITS 


427 


circuits and lights to be used with the main switches, in the cabinets, 
open. Special mention of these circuits is made hereinafter. 

19. BRANCH CIRCUIT LIGHTING CABINETS: All branch 
circuit lighting cabinets shall be flush or wall mounting as noted, and 
shall be constructed of code steel, provided with concealed hinge doors 
with Yale locks and masterkeyed, and all shall have a standard side wiring 
gutter. All branch circuit lighting panels shall be safety type with 
safety type switches in the mains and sub-mains. Bus bar work shall be 
satin finish. Branch circuit buses shall be of Edison Plug Fuse type, and 
each branch circuit shall be equipped with a No. 2645 Bryant panel board 
push switch placed under a sectional dead-front plate. Each switch 
shall have a card holder. Fuses and switches shall be in separate 
compartments. 

20. MOTORS: All motors and starting devices will be furnished and 
delivered to the building by others, but this contractor shall receive and 
set same in place and make all necessary electrical connections. Provide 
a Trumbull, or equal safety type externally operated switch for each 
motor. This contractor shall include in his bid all necessary labor and 
material for connecting the motors complete ready to run. The remote 
control starter for organ motor is to be furnished by others. 

21. SERVICE FUSING CABINETS—SWITCHBOARDS AND 
PANELS: There will be 17 principal switch and fuse cabinets in the 
theatre for the distribution of light and power. These 17 cabinets are as 
follows: 

No. 1—Cabinet “A”—General-Lighting Cabinet for theatre lights. 

No. 2—Cabinet “ B ”—Emergency Service Board for theatre emer¬ 
gency and exit lights. 

No. 3—Cabinet “C”—General-Power Cabinet for theatre power. 

No. 4—Cabinet “D” —Major Remote Board under stage. 

No. 5—Cabinet “E”—Emergency cabinet. 

No. 6—Cabinet “H”—Externally operated power switch for the 

converter. 

No. 7—Cabinet “G”—Front door man’s cabinet for general light 

in lobbys and foyer, etc. 

No. 8—Cabinet “J”—Shop cabinet for all stores and shops. 

No. 9—Cabinet “K”—Ditto for all offices and public lights. 

No. 10—Cabinet “P”—Major Combination Pilot board and 

Dimmer Bank on the stage. 

No. 11—Cabinet “O”—Picture Booth Cabinet for lights and small 

motors in booth. 

No. 12—Cabinet “S” —Sign cabinet for theatre signs. 

No. 13 to 17 inclusive—Five branch cabinets in 5 shops. 

22. CABINET “A:” (Figs. 530 and 535) The main service will enter 
(A r , Fig. 530) the building in the switchboard room which is located under 


428 


LIGHTING CIRCUITS AND SWITCHES 


[Drv. 9 


the stage as shown on the basement plan. Service wires and conduits 
to be brought to this cabinet, from the service Company’s entrance 
(X, Fig. 530) in the alley, by the electrical contractor. The service wires 
(Fig. 550) to feed this main theatre lighting service, cabinet “A,” shall 
consist of 6—600,000 C.M. cables. The service cabinet shall be 



Fig. 535.—General-lighting cabinet—Cabinet “A”—for Indiana Theatre, Terre 
Haute, Ind. (Frank Adam Electric Co.) This is the shop drawing made by the switch¬ 
board manufacturer based on the electrical engineer’s sketch, Fig. 551. 


floor mounting and shall be constructed of No. 10 steel, the doors to be 
equipped with vault handles and plain hinges. Cabinet to have a stand¬ 
ard side wiring gutter. Panel to be l4l>-in. black electrical slate and 
contain the following (see Figs. 535 and 551): 

































































































































Sec. 452] 


THEATRE CIRCUITS 


429 


Circuit 

No. 


1 


Description 


1 1,200-amp., 110-220 volt N.E.C. fused service switch, with 
space for current transformer, feeding the following circuits. 


2 1 100-amp., 3-pole, N.E.C. fuse connection, connected to bus 

behind the current transformers so that separate meter may 
be used, to feed Cabinet “J.” 

3 1 100-amp., 3-pole, N.E.C. fuse connection, connected to bus 

behind the current transformers so that separate meter may 
be used. Spare. 

4 1 30-amp., 3-pole, N.E.C. fuse connection to feed the 44-h.p., 

220-volt motor. 

5 1 200-amp., 3-pole, N.E.C. fuse connection to feed Cabinet 

“G.” 

6 1 400-amp., 3-pole, N.E.C. fuse connection to feed Cabinet 

“S.” 

7 & 8 2 400-amp., 3-pole, N.E.C. fuse connections to feed the 

remote board, “D.” 


23. CABINET “B” (Figs. 530 and 555): The service-switch cabinet 
for the theatre emergency-and-exit lighting will be 100-amp., 3-pole, 
N.E.C. fused, safety-type, externally-operated switch, Trumbull, or 
equal, as approved by the architect. This switch is to be connected 
by 3 No. 6 wires in 1%-in. conduit to a separate set of transformers so as 
to insure independent emergency lighting for all means of exit which are 
used by the public. This contractor shall run 3 No. 6 wires in a 13'4- 
in. conduit (Fig. 550) to cabinet “E’ ’(Figs. 531 and 546) in doorman’s 
closet in lobby. 
























430 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


24. CABINET" C” (Fig. 536): This is the general power cabinet and is 
to be located along side of Cabinet “A” (Fig. 530) and is constructed 
along similar lines. This cabinet will have a standard side wiring gutter. 
Feeders for this cabinet to be 4-2/0 cables in a 2-in. conduit from the 



Fig. 536. —General-power cabinet—Cabinet “C”—for Indiana Theatre, Terre Haute, 
Ind. (Frank Adam Electric Co.) This is the shop drawing made by the switchboard 
manufacturer based on electrical engineers sketch, Fig. 552. 


service company’s entrance (Fig. 530) in the alley, supplying 440-volt, 
2-phase alternating current. The panel for this cabinet (Fig. 536) will 
be 1^-in. black electrical slate, and shall contain (Fig. 552) the following: 


































































































































Sec. 452] 


THEATRE CIRCUITS 


431 


Circuit 

No. 


Description 


1 

2 

3 

4 

5 


6 


7 

8 
9 


1 200-amp., 4-pole, N.E.C. fused service switch, provided with 
necessary test links and meter loops. 

1 100-amp., 4-pole, N.E.C. fuse connection to feed 30-h.p. 
typhoon fan. 

1 100-amp., 4-pole, N.E.C. fuse connection to feed 25-h.p. 
heater fan. 

1 60-amp., 4-pole, N.E.C. fuse connection to feed converter. 

1 60-amp., 4-pole, N.E.C. fuse connection to feed 20-h.p. 
typhoon fan. 

1 30-amp., 4-pole, N.E.C. fuse connection to feed organ motor. 

1 30-amp., 4-pole, N.E.C. fuse connection to feed vacuum 
motor. 

1 30-amp., 4-pole, N.E.C. fuse connection to feed 10-h.p. 
fan motor. 

1 30-amp., 4-pole, N.E.C. fuse connection, spare. 


25. METERING: Provision shall be made for the following meters: 

1. One for total lighting load of the theatre, controlled by 
Cabinet “A.” 

2. One for the total power load of the theatre controlled by 
CABINET “C.” 

3. One for the emergency and exit lighting load of the theatre, 
controlled by Cabinet “B.” 

4 to 8. Five at Cabinet “J” for the 5 shops on 1st floor. See 
also Clause 46. 

This contractor will bring out cables through required meter-fittings 
and provide a neat meter-board, painted black, for the accommodation 
of each meter. The meters will be furnished by others. The contractor 
shall confer with the representative of the local electric-service company 
and with the architect before deciding on the method of arranging the 
meters. 

26. CABINET “P” PILOT BOARD ON THE STAGE (Figs. 537 
and 553): The electrical contractor is to furnish and install complete a 
“Major” dead-front Pre-Selection system as manufactured by the Frank 
Adam Electric Company, St. Louis, Mo., consisting of a pilot-board “P” 
located on the stage as indicated on plans (Fig. 531), and a remote-board 
“D” in the basement under stage (Fig. 530) as shown. 

The pilot-board (Figs. 537 and 553) shall be made up of the number of 
switch units as per schedule following (Clause 27), mounted on an angle- 




















432 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 0 


iron frame enclosed in a steel cabinet made of No. 10 U. S. gauge steel. 
This cabinet shall be provided with a 4-in. mat of No. 10 steel. The 
upper part of the mat shall contain 3 No. 61,777 receptacles and three 
pear-shaped green shades (A and /, Fig. 537) for lighting the pilot-board. 


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Two of these lights shall be controlled by a tumbler switch on the pilot- 
board, and one shall be so connected (Sec. 442) as to indicate whether the 
pilot board is dead or alive. The lower part of the mat shall be provided 
with a 3-wire flush receptacle, Bryant No. 425, ( B , Fig. 537) complete, 







































































































































































































Sec. 452J 


THEATRE CIRCUITS 


433 


with plug attached to one end of 50 ft., of 3-conductor, No, 14 stage 
cable, with a No. 2,642 Bryant Momentary contact push switch on the 
other end of the cable. This is to be so wired (Fig. 538) that the momen¬ 
tary-contact switch will control any or all pilot switches on the entire 
pilot-board, except those for the house lights. 

There shall be 2 No. 2,642 Bryant momentary contact push switches, 
one located at the Door-man’s Station ( y , Fig. 531) and the other one 
on the front wall of the operating booth (x, Fig. 531) between look-outs. 
These switches shall be wired in multiple and connected to the house 
main by 3 No. 14 wires, to control all or any part of the lights in audi¬ 
torium. Provide the necessary number of 7-gang plates (Fig. 537) and 





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Ind. (Frank Adam Electric Co.) 


switches to provide a G. E. flush tumbler switch as per schedule (clause 
28) under tumbler switches on Pilot Board. The tumbler-switch plates 
shall be the same gauge and finish as the pilot-switch plates. Each 
pilot-switch, except the masters, shall be provided with a pilot-light 
(Sec. 443) and color-cap corresponding with the colors of the lights 
controlled by the respective pilot-switches. This pilot-lamp shall 
be connected to the lamp-group controlled by the corresponding pilot- 
switch. Each pilot-switch shall be provided with an etched copper 
name-plate showing the name of the circuit controlled. Provide a 
special plate (Fig. 553) to take push buttons for calling dressing rooms. 

The back of the pilot-board—magazine panels, Fig. 539—shall be 
made up of the required number of bus-bar fuse panels of 1-in. thick 
ebony asbestos, with a 4-in. removal strip of steel between adjacent 
panels. These panels shall be of the polarity type (Sec. 440) and shall 
have wire holes for mains and branch circuits. Provide angle lugs for 
attaching mains to bus. All branch circuits of capacities of from 1 to 
28 




















































































434 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


30 amp. shall be of the Edison-plug-fuse type. All branch circuits of 
30 amp. and over shall have N.E.C. fuses. Provide a name-plate for 
each branch circuit. This name-plate is to be located between bus-bars, 
and to be lettered as per instructions. The electrical contractor shall 
submit a detail shop drawing of these panels (see Fig. 539) for the archi¬ 
tect or his electrical engineer’s approval, before proceeding with this 
work. 



Fig. 539.—Magazine cabinet for the Indiana Theatre, Terre Haute, Ind. (Frank Adam 

Electric Co.) 


In addition to the above pilot switches on the pilot board, there shall 
be 24 double-pole tumbler switches (Figs. 537, 540, and 553); one for each 
branch circuit of the red, white and blue incandescent stage pockets. 
Each tumbler switch is to be connected into the branch circuit between 
the magazine panel and the incandescent stage pocket outlet. 
















































Sec. 452] 


THEATRE CIRCUITS 


435 



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27 . Schedule of Pilot, Magazine and Remote Switches and Dimmers 


436 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 0 


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Sec. 452] 


THEATRE CIRCUITS 


437 


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438 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


28. TUMBLER SWITCHES ON PILOT BOARD “P ” In addition 
to the pilot switches shown in the foregoing schedule there are a number 
of tumbler switches on the pilot board (Fig. 537) which are fed by a 
constant section (Fig. 539) of the magazine panel at the rear of the 
pilot board. There shall be a total of 24-plug fuse circuits on magazine 
panel fed by 3 No. 6 wires from remote board “ D.” The tumbler 
switches (see Figs. 537 540 and 553) are for all outlets lettered “T” 
on plans and control the following: 

T-l Controls 1 10-watt and 3 60-watt lights (Fig. 537) on front and 
rear of pilot board. (Lamp I, Fig. 537) is connected as described 
in Sec. 442.) 

T-2 and T-5 Work lights: Controls the 2 300-watt work lights (Fig. 533) 
in the center of each border light. (See border light specifications.) 
T-3 and T-4 Omitted. 

T-6 Rigging loft: Is a 3-way and controls 6 outlets (Fig. 532) above 
rigging loft. These outlets to be 8B boxes complete with cover 
sockets. These outlets are also controlled by a 4-way switch on 
fly floor, also by another 3-way switch in the rigging loft. 

T-7 Orchestra lights: Is a 3-way and controls 8 duplex flush receptacles 
(Fig. 531) for orchestra stands. The other 3-way switch is at the 
leader’s stand. Get the exact location of this switch from the 
Architect. 

Note: This contractor shall furnish complete 10 Major type, or equal, 
approved music stands wired complete with 10 ft. of cable. 

Note: (Switch No. 221, Figs. 537 and 540). This contractor shall 
also furnish and install complete to the orchestra pit a signal system 
as follows: 1 circuit from the constant buss on the rear of the pilot 
switchboard through a single circuit momentary contact push- 
switch (located on the pilot switchboard) to a cover socket, ’ocated 
under footlight trough in view of the leader of the orchestra. 
T-8 Is a 3-way and controls 2 ceiling outlets with cover socket, also 
6 wall outlets (Fig. 531) on side walls of stage complete with pull 
chain sockets and crescent wall guards. Note all the above outlets 
are also to be controlled by a 3-way switch at one stage entrance 
and a 4-way at the other stage entrance. 

T-9 Dressing rooms: Controls 12 outlets in 4 upper dressing rooms 
(Fig. 533) also 4 outlets in passage ways and stairs to upper 
dressing rooms. 

T-10 Controls 3 outlets (Fig. 532) on fly floor, also 3 outlets on stairway 
to fly floor and rigging loft. These outlets to be complete with 
cover sockets and crescent wall guards. 

T-ll Controls 4 100-watt outlets (Fig. 531) in the property and storage 
space. These outlets to be complete with drop cords, key sockets 
and Loxon guards. 

T-12 Is a 4-wav and controls 10 outlets (Fig. 530) in basement passage 
ways, toilets, stair leading to basement, also one outlet (Fig. 531) 
outside over stage entrance. All to be complete with cover sockets, 


Sec. 452] 


THEATRE CIRCUITS 


439 


except the ones over the stage entrance, and these shall have a goose 
neck of in. conduit complete with a 14-in. R.L.M. Standard 
steel reflector. 

T-13 Controls 12 40-watt outlets (Fig. 530) over make up tables in 4 
dressing rooms in basement. 

Note: All dressing room outlets to be 8B boxes with cover sockets, 
complete with crescent wall guards. 

T-14 Controls 2 300-watt ceiling outlets (Fig. 530) in future chorus 
room. 

T-15 Controls 8 outlets (Fig. 530) in switchboard room, musicians’ 
room and animal room, all with drop cords complete as per T-ll. 
T-16 Controls 12 40-watt outlets (Fig. 530) in basement heater rooms. 
See note under T-ll. 

T-17 Heater outlet: Controls heater outlet (Fig. 530) in basement. This 
outlet to be complete with Bryant No. 558 Heater Control Com¬ 
bination. 

T-18 Controls 8 50-watt outlets (Fig. 533) in organ lofts. 

T-19 Controls 8 60-watt outlets (Fig. 532) in attice space and fan rooms. 
See note under T-ll. 

T-20 Cleaners outlet: Is a 3-way and controls 1 1000-watt outlet (Figs. 
532 and 533) on the gridiron at the center line, 2 ft. behind the 
proscenium wall. This outlet to be complete by this contractor 
with an 18-in. standard R.L.M. steel reflector and mogul receptacle 
equipped with No. 14 stage cable of length to allow the reflector to 
be lowered within 5 ft. of the stage floor. 

29. REMOTE BOARD PANEL “D:” This contractor shall furnish 

and install complete a Major Remote Control Board (Figs. 541 and 554) 
at position (Fig. 530) as indicated on plans. This remote board shall 
be made up of the required number of remote switch panels as per the 
preceding schedule (Clause 27). Each remote switch panel shall contain 
1 100-amp. Cutler-Hammer Major special remote switch, with N.E.C. 
fuse connections of proper capacity for load. The remote switch 
panels shall have back connected studs, and be so connected (Fig. 542), 
to the main buss on the rear of the board, that both the remote switch 
and fuses will be dead when the switch is open. The remote switch 
panels shall be drilled for 30, 60 and 100 amp. N.E.C. fuse connections 
so that it will be possible to change fuse capacity to take care of future 
increases in the load. The entire remote board shall be inclosed in a No. 
10 gauge steel cabinet with both front and rear access doors. This 

cabinet shall be placed so as to be accessible from both front and rear. 

30. SCHEDULE OF REMOTE SWITCH CONTROLS FROM 
PANEL “D” (Fig. 541): 

D-2 White Main controls remote switches No. 5 to 15 inclusive. 

D-3 Red Main controls remote switches No. 16 to 25 inclusive. 

D-4 Blue Main controls remote switches No. 27 to 37 inclusive. 

D-5 Footlights: White Foots controls 150 60-watt lamps fed from 8 
branch circuits (Nos. 49 to 56, Fig. 539) on the rear of pilot switch- 


440 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


board. These circuits to be brought to a pull-box located below the 
stage floor, at the end of the trough near the pilot switchboard. 
Connections between the trough and pull-box are to be made with 
Greenfield Flexible conduit, so that the trough can be removed for 
cleaning without disturbing any connection. Reflector and lining 
of gutter to be furnished by others. Footlights to have 150 White, 



Mo/Jor Remote- 
.Controller/ Switches 



Fig. 541.—Front view of remote board with doors removed, for the Indiana Theatre, 
Terre Haute, Ind. (Frank Adam Electric Co.) This shows the switchboard manu¬ 
facturers shop drawing. 


75 Red, and 75 Blue lights, all of which are 60 watt. The reds and 
blues shall be in the upper row, and the whites in the lower. The 
lights shall be wired on alternate circuits (Fig. 529) all the way across 
the trough. Use No. 12 D.B.R.C. wire for the wiring oUthe foot¬ 
lights. For detail of footlights see Fig. 543. 







































































































































Sec. 452] 


THEATRE CIRCUITS 


441 


D-6 Proscenium strips: White proscenium strips right and left con¬ 
trols 8 300-watt lamps (Fig. 531) fed from 2 branch circuits (Nos. 



Fig. 542.—Wiring diagram of the Major remote board for the Indiana Theatre, Terre 
Haute, Ind. {Frank Adam Electric Co.) This diagram is furnished by switchboard 
manufacturer. 

57 and 58, Fig. 539)"on the rear of the pilot switchboard. Furnish 
and install two “Major” type proscenium strips. These strips 



Fig. 543.—Section showing detail of footlights. 


shall be constructed similar to borders, wired for 3 colors for each 
strip, one circuit for each color, with 4 300-watt type C-lamps 



























































































































442 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


per circuit. This contractor shall furnish 24 color frames for 
the two proscenium strips. Each strip shall be 16 ft. long. Each 
lamp shall be in a separate compartment with suitable groove for 
receiving color slide or frame. These grooves to be the same size as 
the grooves in the borders, so that the frames for the borders and 
prosceniums will be interchangeable. These strips to be equipped 
with a heavy wire mesh guard hinged at one side and provided with 
a catch at the other side. Guards to be made in two sections, mesh 
to be approximately 134-in. square. Prosceniums shall be located as 
shown on plans (Fig. 531) and shall be painted same as the borders. 

Note by Author .—Inasmuch as this Terre Haute theatre is, for the present to be used 
as a moving picture-house only, the proscenium strips are omitted. A platform or 
miniature stage has been built on the stage. This platform is provided with a footlight 
trough which is to contain outlets for 90 60-watt lamps. They are called (Fig. 540) 
platform foots. These 90 outlets are wired on three colors as follows: 30 white, 30 red, 
and 30 blue. The lamps of each color are fed from the two magazine circuits which, 
according to the original specifications, were intended to feed the proscenium strips. 
Thus, if at any future time, it is desired to use the house for vaudeville or “legitimate,” 
the proscenium strips may be provided at a minimum expense. 

D-7 Border lights: White border No. 1 controls 12 300-watt lamps 
(Fig. 533) fed from 3 branch circuits (Nos. 67 to 69, Fig. 539) on the 
rear of the pilot switchboard. This contractor shall furnish 
complete 2 “Majorlite” borders. These borders shall be con¬ 
structed of No. 20 gauge iron, equipped with mogul receptacles 
G.E. No. 159,380 and wired with No. 12 Underwriters’ “slow 
burning” wire, see Code Rule 38e, par. 6. Each lamp shall be in a 
separate compartment with suitable groove for receiving color 
slide or frame. Lamps are to be spaced on 12-in. centers. Each 
border shall be wired for three colors. Border No. 1 shall have 
36 300-watt Mazda C lamps, 12 white, 12 red and 12 blue. Border 
No. 4 shall have 24 300-watt Mazda C lamps, 8 white, 8 red and 
8 blue. This contractor shall furnish 60 color frames for the two 
borders. In addition to the above circuits there shall be a separate 
circuit run to the center of each border to feed a 300-watt work 
light. This light is to be controlled by a tumbler switch located on 
stage switchboard. Four of these work lights may be placed on 
one circuit, but a separate tumbler switch must be provided for 
each light. 

Border No. 1 shall be 37 ft. long. Border No. 4 shall be 25 ft. long. 
This contractor shall install necessary chain hangers and giant 
strain insulators and border light cable for each border. Borders 
shall be painted tw T o coats aluminum inside, and two coats dull 
black outside. Steel cable, counter weights and all other rigging 
furnished by others. In the rigging loft the contractor shall install 
2 large pull boxes of 10 circuits each, located 10 ft. off center, each 
to take care of connections to the magazine panel on rear of pilot 
switchboard. The pull boxes shall have bushed opening for bring¬ 
ing out border light cables which shall be fastened to the box in suc^ 


Sec. 452] 


THEATRE CIRCUITS 


443 


a manner so as to take the strain from the connection to the circuit 
wires. Border light cables shall feed border at its center and shall 
be of length to allow borders to come within 5 ft. of the stage 
floor. Border Nos. 3 and 4 and wiring for same to be omitted. 
Also omit pilot and remote control switches and dimmers for 
same, but arrange space so they can be installed in future. 

D- 8 White border No. 2. Blank. 

D- 9 White border No. 3. Blank. 

D-10 White border No. 4. (Same as white border No. 1 except to be 
25 ft. long with 24 300-watt lights on 3 colors.) 

D-ll Cradle spots: There will be a cradle (Fig. 544) or swinging bridge 
furnished by others but this contractor shall furnish and install 
all necessary electrical connections for 9 1.000-watt spot outlets on 



Fig. 544.—Cradle for cradle spots. (A board floor is laid on bottom of cradle.) 

this cradle installed in the following manner: 3 1,000-watt outlets 
are to be switched on D-ll; 3 1,000-watt outlets on D-22; and 
3 1,000-watt outlets on D-33. This contractor shall install a pull box 
(Fig. 533) flat on the rigging loft at point as indicated on the plans. 
From this pull box hang 1 18-conductor, No. 12 border-light cable 
of sufficient length to allow the cradle to be lowered to the stage 
floor. This cable to feed into a pull box on the rail of the cradle, 
and from there to 9 10-amp. No. 7711 flush receptacles mounted 
equal distances apart all the way across the rail of the cradle using 
conduit and condulets. 

D-12 Balcony floods: White balcony floods— furnish 6 1,000-watt 
balcony flood lamps with color frames on three colors, white, red 
and blue, and install 6 10-amp. flush receptacles (Fig. 533) in the 
front wall of the operating room above the ledge for attaching 
6 1,000-watt nitrogen spot lights. These outlets to be wired for 
3 colors, with 2 outlets per color. Use C. H. Co.’s, No. 7711 flush 
receptacle. Confer with architect for exact location of these 
outlets. 

D-13 Orchestra spots: White orchestra spots— furnish 6 1,000-watt 
orchestra spot or flood lamps with color frame. Furnish and 




























































444 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


install 6 10-amp. flush receptacles (Figs. 533 and 534) above main 
ceiling, one at each of the rectangular openings. These outlets are 
to be equipped as per outlets under D-12 and are for 1,000-watt 
spots. 

D-14 Stage pockets: White incandescent stage pockets —controls 8 15-amp. 
receptacles fed from 8 branch circuits (Nos. 59 to 66, Fig. 539) on 
the rear of the pilot board. Contractor shall furnish and install, 
where shown on plan (Fig. 531) 8 stage pockets, three on each side 
of the stage and two in the rear of the stage. Four (4) of these 
pockets shall have 1 35-amp. arc, and 3 15-amp. incandescent 
receptacles, and four (4) shall have 3 15-amp. incandescent recep¬ 
tacles to be Kliegl, Major, or equal, as approved by the architect. 
These stage pockets shall be set flush in the stage floor and shall be 
provided with steel frames. The steel frames shall be insulated 
from the conduit system. Contractor shall furnish a total of 4 arc 
plugs and 24 incandescent plugs for these pockets. Feeders to 
each arc receptacle shall be No. 6, D.B.R.C. wire, and to each 
incandescent No. 12 wire. 

JD-15 Stage arc pockets —controls 4 35-amp. arc receptacles fed from 
4 60-amp. N.E.C. fuse circuits (Nos. 226 to 229, Fig. 539) on the 
rear of the pilot switchboard. 

D-16 Red foots —controls 75 60-watt lamps fed from 4 branch circuits 
(Nos. 70 to 73, Fig. 539) on the rear of the pilot switchboard (see 
detail of footlights, Fig. 543). 

D-17 Proscenium strips {red) right and left —controls 8 300-watt lamps 
(Fig. 531) fed from two branch circuits on the rear of the pilot 
switchboard (see note under D-6.) 

D-18 Red border No. 1—controls 12 300-watt lamps (Fig. 533) fed from 
three branch circuits on the rear of the pilot switchboard. 

D-19 Red border No. 2. Omitted. 

D-20 Red border No. 3. Omitted. 

D-21 Red border No. 4 (see D-10). 

D-22 Red cradle (see D-ll). # 

D-23 Red balcony floods , same as D-12. 

D-24 Red orchestra spots , same as D-13. 

D-25 Red incandescent pockets —controls 8 15-amp. receptacles fed from 
8 branch circuits on the rear of the pilot switchboard. 

D-26 Omitted. 

D-27 Blue foots —controls 75 60-watt lamps fed from 4 branch circuits 
on the rear of the pilot switchboard (see Fig. 543). 

D-28 Blue proscenium strips right and left —controls 8 300-watt lamps 
fed from 2 branch circuits on the rear of the pilot switchboard 
(see note under D-6). 

D-29 Blue border No. 1—controls 12 300-watt lamps fed from 3 branch 
circuits on the rear of the pilot switchboard. 

D-30 Blue border No. 2. Omitted. 

D-31 Blue border No. 3. Omitted. 


Sec. 452] 


THEATRE CIRCUITS 


445 


D-32 Blue border No. 4 (see D-10). 

D-33 Blue cradle (see D-ll). 

D-34 Blue balcony floods, same as D-12. 

D-35 Blue orchestra spots, same as D-13. 

D-36 Blue incandescent stage pockets —controls 8 15-amp. receptacles fed 
from branch circuits on the rear of the pilot switchboard. 

Note: There shall be one tumbler switch located on the pilot 
switchboard for each of these receptacles. 

D-37 Blank. 

D-38 Auditorium main, controls switches Nos. 39 to 47. 

D-39 Side wall coves: Amber —Controls 64 200-watt lamps (Fig. 534) 
fed from 12 branch circuits on the rear of the pilot switchboard. 
This contractor shall furnish and install complete 192 X-Ray No. 
61,0 reflectors for 200-watt lamps placed on 12-in. centers in the 
two side wall coves and arranged on three-color wiring. The 
reflectors to be complete with holders, sockets and wire troughs. 
There will be 64 200-watt lamps for the amber, 64 200-watt lamps 
for the red, and 64 200-watt lamps for the blue. This contractor 
shall furnish 192 color frames and color screens for the auditorium 
coves. 

D-40 Organ grill balustrades: Amber —Controls 10 250-watt lamps 
(Figs. 533 and 534) fed from 2 branch circuits on the rear of the 
pilot switchboard. This contractor shall furnish and install com¬ 
plete 30 X-Ray, No. 800, projector reflectors for 250-watt lamps, 
placed in the two organ ballustrades, arranged on three-color 
wiring. The reflectors to be complete with color screen holders 
and color lenses, also sockets and holders. There will be 10 250- 
watt lamps for the amber, 10 250-watt lamps for the red, and 10 
250-watt lamps for the blue. These to be arranged for flood 
lighting the proscenium arch and organ grills. 

D-41 Behind organ and oriole grills: amber —Controls 112 40-watt 
lamps (Figs. 533 and 534) fed from 4 branch circuits on rear of 
pilot switchboard. This contractor shall furnish and install 
complete approximately 104 ft. of trough reflectors of various 
lengths to fit behind the art glass of the above places. There will 
be eight 10-ft. sections for placing behind the art glass plaques at 
either side of the organ grills. There will be 4 6-ft. sections 
for placing behind the art glass plaques at the two orioles. Each 
reflector shall be wired for three colors with 40-watt lamps on 
4-in. centers. Furnish detail drawings of these reflectors for 
architect’s approval. Install 312 40-watt lamps on three colors in 
the side wall plaques, grills and orioles. There are to be 112 
40-watt lamps for the amber, 112 40-watt lamps for the red, and 
112 40-watt lamps for the blue. The three colors are to be alter¬ 
nated the full length of each trough reflector. 

D-42 Controls red, same as D-39. 

D-43 Controls red, same as D-40. 


446 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


D-44 Controls red , same as D-41. 

D-45 Controls blue , same as D-39. 

D-46 Controls blue , same as D-40. 

D-47 Controls blue, same as D-41. 

D-48 Controls feeders to magazine circuits “A” to “H” inc., for fusing 

pilot board. 



Fig. 545.—Front doorman’s cabinet 
—Cabinet “ G”—for Indiana Theatre, 
Terre Haute, Ind. (Frank Adam Elec¬ 
tric Co.) This shows the switchboard 
manufacturer’s drawing. 


31. CABINET “ G ”—FRONT 
DOORMAN’S OR LOBBY CABI¬ 
NET: This cabinet (Fig. 545) is for 
all lights (except emergency and sign) 
in the front portion of the building 
and is located in the doorman’s closet 
(Fig. 531) as indicated on plans. 
This cabinet is to be wall mounted 
and shall contain a bus bar type 
panel with a 100-amp. no fuse knife 
switch for the mains and safety type 
push switch for all circuits under 
20 amp. The fuses for the branch 
circuits shall be in a separate compart¬ 
ment. Each switch shall be provided 
with a card holder. This cabinet 
is to be connected to circuit No. 5 in 
Cabinet “A” by 3 No. 0 wires in a 
2-in. conduit. 

Note: Circuits G-33 to G-36 are 
not switched and must be placed 
ahead of main switch. 

32. SCHEDULE OF CONTROLS 
—CABINET “G”: 

G-l and G-2 Controls 2 1,320-watt 
circuits to center ceiling outlet (Fig. 
533) in rotunda. Fixture by others. 
G-3, G-4 and G-5. Omitted. 

G-6 Controls 4 150-watt bracket 
outlets (Fig. 532) on side walls 
of upper part of rotunda. 

G-7 Same as G-6. 

G-8 Controls 2 300-watt bracket 
outlets (Fig. 531) on side walls 
of promanada. 

G-9 Same as G-8. 

G-10 Controls 1 1,000-watt floor out¬ 
let (Fig. 531) on promanada. 


G-ll Omitted. 


G-12 Same as G-10. 
G-13 Omitted. 





































































Sec. 452] 


THEATRE CIRCUITS 


447 


G-14 Same as G-10. 

G-15 Omitted. 

G-16 Same as G-10. 

G-17 Omitted. 

G-1S Controls 15 40-watt soffitt outlets (Fig. 531) in promanada. 

G-19 Same as G-18. 

G-20 to G-22 Omitted. 

G-23 Controls 4 100-watt outlets (Fig. 531) on ceiling of promanada. 
G-24 Controls 4 150-watt base plug outlets (Fig. 531) in the promanada. 
G-25 Controls 6 100-watt base plug outlets (Fig. 531) in the promanada. 
G-26 Omitted. 

G-27 Controls 6 100- and 1 50-watt outlets (Fig. 533) in screening 
room. 

G-28 Controls 2 300-watt outlets (Fig. 531) for newel posts on stairs in 
promanada. 

G-29 Controls 8 75-watt outlets (Fig. 531) in ceiling over fountain. 

G-30 Omitted. 

G-31 Controls (Fig. 531) 2 50-watt outlets in men’s toilet, 6 50-watt 
outlets in ladies parlor and toilet, 1 50-watt base outlet in ladies 
parlor, and 1 100-watt ceiling outlet in ladies parlor. 

G-32 Signs: Controls 6 25-watt sign outlets (Fig. 531) over doors. This 
contractor shall furnish and install complete 6 No. 19,424 Polaralite 
signs made by I. P. Frink Company. These signs to have the 
following lettering; “Balcony,” “Check Room,” “Ladies Parlor,” 
“Smoking Room,” “Aisle 1,” “Aisle 2,” and baby spot in proma¬ 
nada ceiling. 

G-33 Feeds 6 60-watt, ceiling outlets (Fig. 531), and 4 60-watt base 
plugs in box office. 

G-34 Feeds 1 60-watt outlet in doorman’s closet, 1 60-watt outlet in 
Check Room, 1 60-watt outlet in Janitor’s closet, 1 60-watt outlet 
in Advertising Room, 1 60-watt outlets in ushers’ room. All these 
outlets to be drop cords. Also 4 60-watt ceiling outlets and 1 
60-watt base plug outlet in Manager’s Office. 

G-35 Feeds Cabinet “0” (Fig. 531 )in operator’s booth with 2 No. 12 
wires. 

G-36 1000-watt machine outlet (Fig. 533) in screening room. 

G-37 to G-42 Controls 64 100-watt outlets (Fig. 533) in the cove in upper 
part of the rotunda. 

G-43 Controls 4 150-watt outlets (Fig. 534) on ceiling over balcony, For 
cleaners’ outlets. 

G-44 Same as G-43. 

33. CABINET “E”—EMERGENCY CABINET: Cabinet “E” 
(Fig. 546) is the emergency cabinet and is located (Fig. 531) along side of 
Cabinet “G.” This cabinet and panel to be constructed similar to 
Cabinet “G,” and shall have a 100-amp. main line remote-controlled 
switch (Fig. 546), not fused, with safety-type push switches in the 
branches. This cabinet is connected to the emergency switch cabinet 


448 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


“B” by 3 No. G wires in an -in. conduit. This remote switch is 
controlled from the momentary-contact switch (Fig. 531) in the 
rotunda. 

34. SCHEDULE OF CONTROLS FROM CABINET “E”: 

E-l Controls 4 150 -watt 

bracket outlets (Fig. 531) 
on the lower portion of 
the side walls of the ro¬ 
tunda. 

E-2 Controls 5 150-watt 

bracket outlets (Fig. 531) 
on the lower portion of 
the side walls of the ro¬ 
tunda. 

E-3 Omitted. 

E-4 Controls 2 3 00-watt 

bracket outlets (Fig. 531) 
on pilasters in proma- 
nada. 

E-5 Same as E-4. 

E-6 Same as E-4. 

E-7 Controls 6 100-watt ceil¬ 
ing outlets (Fig. 531) in 
passage ways leading to 
promanada. 

E-8 Controls 6 100-watt out¬ 
lets (Fig. 531 and 533) on 
stairs to balcony. 

E-9 Controls 8 60-watt side 
wall bracket outlets (Figs. 

531 and 533) in audi¬ 
torium. 

E-10 Same as E-9, except on 
opposite side. 

E-ll Controls 14 50-watt out¬ 
lets (Fig. 533) on main 
ceiling over rear of bal¬ 
cony. 

E-12 Controls 8 50-watt 
bracket outlets (Figs. 531, 

532 and 533) on emerg¬ 
ency stairway to balcony. 

E-13 Controls 7 50-watt bracket outlets (Figs. 531, 532 and 533) 
on stairs to balcony. 

E-14 | Aisle Lights: Control 88 10-watt outlets (Fig. 533) for aisle lights. 
E-lSjThis contractor shall furnish and install complete 62 Brookins 
E-l61 Aislelites and 26 flush cabinet aisle lights with glass covers. 



Fig. 546. — Emergency cabinet — Cabinet 
“E”—for Indiana Theatre, Terre Haute, 
Ind. (Frank Adam Electric Co.) 



























































Sec. 452] 


THEATRE CIRCUITS 


449 


These flush cabinet fixtures with glass covers are to be installed 
in boxes, lamps, stairs, and on partitions. 

E-17 Controls 22 10-watt inside exit lights (Figs. 531 and 533). Con¬ 
tractor to furnish EXIT boxes, sockets, and art glass signs. 

E-18 Controls 14 25-watt outside exit lights (Figs. 531 and 533). Each 
outlet to be water proof. 

E-19 Controls 5 100-watt ceiling outlets in promanada. 

E-20 Omitted. 

35. CABINET “S”—SIGN CABINET: This cabinet (Fig. 547) 
is of special construction and is shown on Fig. 556 attached here- 


b. 


-24-— 


->j< - -6"- - >f< - - - =■' -10 -— t—>] 



Fig. 547.—Sign cabinet- 


-Cabinet “S”—for Indiana Theatre, Terre Haute, Ind., 
{Frank Adam Electric, Co.) 


with and which forms a part of these specifications. Cabinet “S” is 
located in (Fig. 531) closet above Cabinet “E” and is of special construc¬ 
tion. Feed Cabinet “S” from Cabinet “A” with 3 300,000 C.M. 
cables in 2^-in. conduit. 

36. SCHEDULE OF CONTROLS FROM CABINET “S”: 

S-l Cornice lights: Is a 3-pole, 60-amp. standard knife switch feeding 
6 branch circuits for 68 75-watt lamps (Fig. 533) in soffitt of 
cornice. This contractor shall furnish and install these outlets 
29 




























































































































































450 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


complete. Confer with contractor for terra cotta, and with the 
architect for the method of installation. 

S-3 Canopy lights: Is the same as S-l but it feeds 6 branch circuits 
for 99 75-watt outlets (Fig. 531) in inside section of canopy. 

S-4 Main sign: This is a 100-amp. 3-pole knife switch feeding 3 No. 1 
wires to roof, where flasher box will be installed by others. 

S-2 Canopy lights: Same as S-l feeding 8 branch circuits for 132 
75-watt outlets (Fig. 531) around edges of canopy. This con¬ 
tractor shall furnish and install 17-A boxes with P & S cover sockets 
for all canopy outlets. 

S-5 Attraction sign on canopy: Same as S-4 feeding 3 No. 4 wires 
for sign on front edge of canopy. 

S-6 Future sign: Same as S-4 feeding 3 No. 2 wires to an outlet over 
canopy at center of building for future sign. 

37. CABINET “H” IN OPERATING ROOM: Cabinet “H” is a 


K> 


> 

/«- 

>1 

T H 


i ^ 

1 


§ 1 


;i 


■ 'v 



!5- 


-»/1< 


: \ Fuses Gc; 


m. 


«« 


in 


4-pole, 60-amp., N.E.C. fused, safety-type, externally-operated knife- 
switch located in operating room (Fig. 531). 

38. PICTURE BOOTH—CABINET “H”: This switch is to be fed 
by 4 No. 8 wires in a 1-in. conduit from fuse connection No. 4 of cabinet 
“C” (Fig. 536) and is to feed the motor generator. The motor-generator 
set and panel will be delivered to the building by the owners, but this 

contractor shall receive same, set it 
in place, and make all necessary 
electrical connections. From the 
panel furnished with motor generator 
set, the contractor shall run l^-in. 
conduit and 2 No. 4 wires to each 
picture machine. These conduits 
shall run through the concrete floor 
and turn up 24 in. from the front 
wall of the booth on the center of the 
projection opening. Furnish type 
“A” condulet with 2-hole cover 
located 3 in. above the floor. The 
No. 4 wires in each conduit shall be 
long enough to extend to switch 
terminals on machines without splicing. At the same location, contractor 
shall install a 3^-in. conduit with 2 No. 14 wires from Cabinet “O” for 
the motors on the picture machine, these conduits to run to the 4-circuit 
Cabinet “O.” 

39. CABINET “0 Fuse panel Cabinet “0” (Fig. 548) on the wall 
of the booth (Fig. 531) is for booth lights and motors on picture machines 
and rewind. This cabinet is fed by 2 No. 12 wires (see G-35) from 
Cabinet “G.” Contractor shall install a flush push switch controlling a 
flush receptacle at the location of the rewind shelf for the rewind motor. 
From this same cabinet the contractor shall install a push switch at 
the door to control 3 drop-cord outlets, located over the head of each 


Slate Base--'' \ 

Push-Button 5nap Switches'' 

Fig. 548. —Panel for picture booth 
cabinet—Cabinet “O”—for Indiana 
Theatre, Terre Haute, Ind. (Frank 
Adam Electric Co.) 














Sec. 452] 


THEATRE CIRCUITS 


451 


machine, and one over the rewind shelf, also 1 outlet in vestibule and 1 in 
converter room. These drop cords to be equipped with porcelain sockets 
and guards with cords long enough to reach within 3 ft. of the floor. 
Install 2 No. 6 wires in a 1-in. conduit run from the motor generator 
panel through the floor of the booth to a point on the front wall of the 
booth 18 in. above the floor under the spotlight opening. Furnish a 
2-hole type “ A” condulet. The owners will deliver to the building three 



Fig. 549.—Side view of pilot board for Indiana Theatre, Terre Haute, Ind., showing 
location of dimmers, pull-box and magazine cabinet. (Frank Adam Electric Co.) 

picture machines and one spotlight. This contractor shall receive same, 
set them in place and make all necessary electrical connections. 

40. DIMMERS: This contractor shall furnish and install 1 bank of 
Cutler-Hammer Interlocking 110-step theatre dimmers, equipped with a 
slow motion cross interlock lever-shaft drive, arranged as in Fig. 537, 
construction for mounting at the rear (Fig. 549) of the pilot board 
(Fig. 531) on the stage. Each dimmer lever is to have an indicator 





























































452 


LIGHTING CIRCUITS AND SWITCHES 


[Dry. 9 


attachment. Plates to be arranged 3 high with the master levers in the 
center of the bank. Dimmers to be of the wattage as per schedule under 
pilot board, Clause 27 and Fig. 540. The house dimmers shall be 
designed for continuous duty. 

41. TELEPHONE SYSTEM: This contractor shall furnish and 
install complete in an operating condition 12-station system, location of 
•stations as follows: 

1. Manager’s office, combination set (Fig. 531). 

2. Operator’s booth, combination set (Fig. 531). 

3. Box office, combination set (Fig. 531). 

4. Main doorman, flush type wall phone (Fig. 531). 

5. Balcony tunnel telephone, flush type as directed (Fig. 533). 

6. Balcony tunnel telephone, flush type as directed (Fig. 533). 

7. Musicians’ room, wall type (Fig. 530). 

8. Screening room, wall type (Fig. 533). 

9. Pilot board on blank panel, combination set. 

10. Orchestra leader, combination set (Fig. 531). 

11. On pilaster in promanada, flush type (Fig. 531). 

12. Office No. 6, combination (Fig. 532). 

These telephones shall be of the Stromberg-Carlson make and shall be 
of the inter-communicating type with selective ringing and common 
talking lines. Provide a bell ringing transformer for the ringing for these 
telephones, and a Patterson Battery set for the talking side. Provide 
buzzers for all combination telephones. Others shall have bells. 
Provide lead covered telephone cable, installed in %-in. conduit for the 
above telephones. 

42. CONDUITS FOR PUBLIC TELEPHONES: This contractor 
shall install proper conduit and pull boxes for the public telephone sys¬ 
tems as used in Terre Haute providing outlets (Fig. 531) as follows: 
One outlet in the box office; one outlet in the manager’s office, and one 
outlet in each of the public telephone booths (Fig. 531) in the lobby. 
Conduit only to be installed by this contractor. 

43. DRESSING ROOM CALLS: There shall be furnished and 
mounted on Pilot switchboard (Fig. 553) a series of 20 push buttons for 
operating the call bells (Fig. 530) in each dressing room, the help’s room, 
musicians’ room, property room and animal room. A bell-ringing trans¬ 
former shall be installed for operating the bells. All wires for this system 
shall be lead-covered installed in conduit as specified under telephones. 

44. STORES, OFFICES, SHOPS AND STORE ROOMS: This 
contractor shall install all necessary wiring for the stores, offices, and 
shops, in the theatre building, including switches, flush receptacles, etc., 
all ready for the attaching of the fixtures and ceiling fans. The ceiling 
fan outlets will not be on any switch. There will be a separate cut-out 
and switch cabinet in each of the five shops (Fig. 531) under this con¬ 
tract. These cut-out cabinets will be located as shown on electric plan 
(Fig. 531). These will be of .the flush type, steel construction with mat 


Sec. 452] 


THEATRE CIRCUITS 


453 



o 

O 




73 

d 


3 

c3 

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<D 

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<D 

H 

qT 

o3 

o> 

Eh 

c3 

a 

c3 

a 

HH 

U 

O 

*+* 

B 

a 
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bo 
e3 

*3 

<3 

■d 

<u 

fit 


o 

*o 

to 


a 

w 


































































































































454 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


and door, having porcelain cut-outs of the number as shown on plans, 
inside the cabinet with push button switches in the steel mat of the 
cabinet for control of lights in each shop. 


an j? _ ml, 

"|£0|0-A| 


( 

} 

( 

5 

(T> 100-A -cy 



M3-I00-A© 

© lOO'A*-o 



-a-100-A® 

1,000 Amp. Current ^ 
Transformer -A 
® 30-A • -a 

J 


J 

—-30-A® 

© 200-A mu— 



—o-lOOA® 

©400'A -a— 



—a-400-A® 

©400-A M3— 



—co-400-A© 

©400-A m3— 



—Q* 400-A® 

TT 

1 

1 

I 1 


<c <c <: <: < <c < 

<6000 o o o 
o lO o o o o o 

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® © 0 © © © © 


Fig. 551.—Panel for cabinet “A.” 
Electrical engineer’s sketch included in 
specifications. See Fig. 535 for shop 
drawing. 



Fig. 552. —Panel for general-power cab¬ 
inet—cabinet “C.” This sketch accom¬ 
panies architects specifications. 


45. CABINET “J”: This cabinet will be located in the passage 
of the basement (Fig. 530) under the shops on 7th St., as shown on the 

■Push-Buttons For 



Fig. 553.—Electrical engineer’s sketch of pilot board, “P”- 

for wiring the theatre. 


-included in the specifications 


electric plan. This cabinet will be wall mounting, having a slate panel 
on which will be mounted 1 200-amp. non-fused main line switch, 5 
30-amp., N.E.C. fused, branch circuits for the five stores, 1 60-amp., 




























































































































































Sec. 452] 


THEATRE CIRCUITS 


455 


branch fuse connection for Cabinet “K,” and 1 60-amp. fuse, spare. 
This cabinet will be fed by 3 No. 2 wires in 13^-in. conduit from Cabi¬ 
net “A.” 


Pull Box 

2 

5 

6 

7 

Blank) 

Blank 

10 

11 

12 

13 

14 

15 

3 

16 

n 

18 

c 

C5 

CO 

X 

c 

o 

CO 

21 

22 

23 

24 

25 


4 

27 

25 

29 

Blank 

Blank 

32 

33 

34 

35 

36 


38 

39 

40 

41 

42 

43 

44 

45 

46 

47 

48 



8 

§ 


1 

•K. 

I 

§ 

>o 


Jb 




Fig. 554.—Remote board “ D.” Electrical engineer’s sketch accompanying 

specifications. 

46. CABINET “K”: This cabinet feeds all “K” outlets in all offices, 
and also public lighting lettered “K-l” to “K-4.” This cabinet will be 



Fig. 555.—Cabinets “ E,” “ B ” and “ G.” 


located (Fig. 532) in the janitor’s closet on the 2nd floor as shown on the 
electric plan, and will contain 14 circuits arranged for separate metering 
of the 7 offices and 1 meter for the 4 circuits for the public lighting. All 



































































































































































456 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


wiring to the offices will be complete by this contractor, ready for the 
fixtures which will be furnished by others. This cabinet is fed by 3 
No. 8 wires from Cabinet “ J.” 

47. CABINETS AND SWITCHBOARD DIAGRAMS: Attached 
to these specifications are four blue prints (Figs. 550, 551, 552, 553, 554, 
555 and 556) showing the diagramatic arrangement of all panels and 
switch boards on this job. Each outlet on the plan is keyed with a letter 
and numberal indicating which switch in the various cabinets the outlet 


_Q_Q_ Q_Q O. 


Fed From 5-1 
a —o—o—c—o o'* 


O O Qc 

Fed From 
TTTT o 


Q Q Q 


o 


5-3 


OOO O + QQ. Q -Q- 

Fed From 5-2 


OOOO 0000' 


S-l 

60-Amp. 

3-Pole 

Knife 

Switch 


S-2 


Same 
As 5-1 


S-3 


Same 
As 5-1 


S-4 

100-Amp. 
3-Pole 
Knife 
Switch 


Same 
As 5-4 


5-6 


Same 
As 5-4 


I- C a b i n e 1 


“ S ” 


Cabinets ,J And K 
Are Special Meter 
Control Panels. See 
Specifications 


Push-But ton Switches\ Fuses 


• 

- 


»\ 

1' 

t 

1 

60 Amp., 
4-Pole, 
N.E.C. 
Fused, 
Externally- 
Operated 
Switch 


o 

o 

o 

o 

1 N 

\ \ 

• 4 • • 

• • • • 

V 

o 

0 

o 

o 



• w 

Feeders 


-Cabinet “H 

m- 

Cabinet 

‘0” 


Fig. 556.—Cabinets “ S,” “ H” and “ O.” Sketch accompanying specifications. 


is controlled from. To wit: Outlet “G”-10 is controlled by switch No. 10 
in Cabinet “G 

48. GUARANTEE: All material and workmanship shall be of the 
best kind and must meet with the approval of the owner and architect, 
who reserve the right to reject any material not in accordance with these 
specifications either before or after installation. Drawings of cabinets 
and lay-outs must be submitted to the architect also actual samples 
of wire which is to be used before they are either contracted for or pur¬ 
chased by the electrical contractor. 
















































Sec. 452] 


THEATRE CIRCUITS 


457 


QUESTIONS ON DIVISION 9 

1. Name four principal requirements which should be considered in laying out the 
circuits for lighting a theatre. 

2. What two types of construction are used for theatre service wires? What condi¬ 
tions determine which type is preferable? 

3. Name the three separate services with which theatres are usually provided. 
Under what conditions may the general-power service sometimes be dispensed with? 

4. Name the two services which a theatre must have. What determines the wire- 
size for each? 

5. What is the function of the general-power service? What motors in the theatre 
are not generally fed by the general-power service? 

6 . What is the function of the emergency service? 

7. What are emergency lamps? 

8 . Why is it desirable that the emergency service and the general-lighting service 
be connected to different street mains? Where it is impractical to do this, what other 
methods of connecting the emergency service to the source of supply may be used? 
Make a diagram to illustrate each method. 

9. When a storage-battery energy-supply is provided for the emergency service, 
w r hat method is frequently used to connect the regular emergency-service line and the 
storage-battery system to the emergency-circuit feeder? Make a diagram to illustrate. 

10. Why is trouble more likely to occur on the general-lighting service than on the 
emergency service? 

11 . Make a sketch of a non-interchangeable arc-and-incandescent stage pocket and 
explain why either plug will only fit its own receptacle. 

12. What is the function of the general-lighting service? What lamps receive energy 
from this service? 

13. By what type of current and at what voltage is the energy for lighting a theatre 
usually delivered? That for driving the motors of a theatre? 

14. With what must each service be equipped? How must the service switch and 
service fuses be wired? How should they be mounted? 

15. What type of service fuses is generally used for capacities less than 800 amp.? 
What kind of protection is usually provided when the capacity is greater than 1,000 
amp.? 

16. What is a service hoard? Where are the service boards for a theatre usually 

located? Why? . 

17. Why is it sometimes undesirable to locate the service boards in the stage-base¬ 
ment? Make a sketch to illustrate. 

18. Make a diagram to illustrate the general scheme of the circuit-layout which is 
ordinarially used for theatres. 

19. Of what does the general-power cabinet usually consist? Under what conditions 
may the general-power cabinet be located at some point ■which is remote from the 
service entrance? 

20. From what is the converter panel fed? 

21. Of what does the emergency service hoard usually consist? 

22. Why are the emergency service board and the emergency distribution panel not 
usually combined? 

23. Define emergency cabinet. Of what does this cabinet usually consist? Why is it 
advisable to omit the switches in the branch circuits of the emergency cabinet. 

24. Where should the emergency cabinet be located? Why? 

25. What two types of main switches are generally used in the emergency cabinet? 
When a remote-controlled main switch is used to control the emergency cabinet, where 
is the controlling momentary-contact switch usually installed? 

26. What is the purpose of the emergency lamps? About what wattage per square 
foot of floor space is generally required to accomplish this purpose? 

27. What lamps are on the emergency circuit? 

28. How many sets of fuses can any emergency lamp have between it and the main 
emergency-service fuses? 


458 


LIGHTING CIRCUITS AND SWITCHES 


[Div. 9 


29. Explain why the exit-sign lamps are not, strictly speaking, considered to be 
emergency lamps. 

30. Of what does the general-lighting cabinet usually consist? 

31. Name the distribution centers or cabinets which are ordinarily fed from the 
general-lighting cabinet. 

32. Where is the sign cabinet usually located? Under what conditions may it be 
installed in a different location? What types of switches are used in sign cabinets? 
When the sign cabinet is remote-controlled, where are the controlling-momentary- 
contact switches usually installed? 

33. By what other name is the front-doorman's cabinet sometimes called? Where is 
it nearly always located? Of what does it consist? What lights are fed from this 
cabinet? What lights should be connected ahead of the main switch in this cabinet? 
Why? 

34. Of what does the picture-booth cabinet generally consist? Where is it located? 
From what cabinet is it fed? What energy-consuming devices does it serve? 

35. Explain how a profitable current-saving may sometimes be effected by properly 
selecting the circuits to which the lamps in the front portion of the theatre are connected? 

36. Under what conditions is a dressing-room cabinet used? From what is the 
dressing-room cabinet fed? What lamps does it serve? When a dressing-room cabinet 
is not used, where is the distribution center for the lamps which it ordinarily serves? 

37. For what purpose is a shop cabinet used? From what cabinet is it fed? Explain 
two methods of metering the energy which passes through the shop cabinet. 

38. From what is the stage switchboard fed? What lights are generally controlled by 
the stage switchboard? 

39. Define: (a) House lights. ( b ) Stage lights, (c) Work lights. What are the 
lamp-colors which are generally used for the house and stage lights? In what pro¬ 
portions are these colors generally installed? 

40. Define the following terms: (a) Remote-control switchboard. ( b ) Remote board. 

( c ) Pilot board. ( d) Individual pilot switch, (e) Sub-master pilot switch. (/) Master 
pilot switch. 

41. Define and make a sketch to illustrate each of the following: (a) Switchboard 
feeder. ( b ) Stage-main switch, (c) House-main switch. (d) Color-main switch, (e) 
Magazine switch. (/) Magazine subfeeder, (g) Magazine panel, (h) Magazine circuit. 

42. Draw a sketch to illustrate the general scheme of circuit control as is provided on 
stage switchboards. 

43. Name the principal requirements of stage switchboards. What is probably the 
most necessary requirement? 

44. Where is the stage switchboard usually located? Why? 

45. What kind of stage switchboard is required by the Code? 

46. What is meant by a manual stage switchboard? A remote-control stage switchboard? 

47. Theoretically, what two methods of remote control of stage switchboards may 
be employed? Which type is used in practice? 

47. Give the classification of manually-operated, dead-front stage switchboards. 
Define each class? Explain how each is operated. 

48. Explain how the similarity in control between interlocking and non-interlocking 
switchboards is obtained. 

49. What is the function of a grand-master lever on an interlocking, manually-operated 
switchboard? Of pre-set master levers. 

50. Make a sketch to illustrate the relative location of the dimmers, switchboard and 
magazine panel. What other arrangements are sometimes used? 

51. What is the ampere rating of the smallest size magazine switch that is generally 
used on a stage switchboard? 

52. Name one of the principal types of remote-control stage switchboards. 

53. Name the advantages of the Major Pre-Selective Control System. 

54. Define pre-selective control. 

55. Name the two essential elements of the Major system. 

56. In the Major system, where may the dimmers be mounted? 

57. Describe the operation of the remote-controlled switch that is used in connection 
with the Major system. 


Sec. 452] 


THEATRE CIRCUITS 


459 


58. Make a sketch of and explain the operation of the Major pilot switch. Draw a 
symbolical wiring diagram of the Major pilot switch. 

59. Name the two switches contained in a Major pilot switch, and explain why each 
is so named. 

60. Make a sketch of a single lamp-group which is controlled by a remote-controlled 
switch and a pilot switch to show the circuit diagram. Explain its operation. 

61. Draw a ciicuit diagram of six remote-controlled switches, which are controlled by 
six individual pilot switches. Also show how two sub-master pilot switches are con¬ 
nected so that each will control three of the individual pilot switches; and a master pilot 
switch to control the entire group. Explain the operation. 

62. When is a single-pole sub-master remote-controlled switch used for an alternating- 
current system? For a direct-current system. Why is it necessary to provide this 
single-pole sub-master remote-controlled switch. Explain by example. Show by 
sketch how two such switches would be connected into the installation, a sketch of which 
was drawn in Question 61. 

63. Classify the switches on a Major pilot board and tell what the switches of each 
classification control. 

64. How are the stage pilot switches connected? The house pilot switches? 

65. What type of switch is employed on the Major board to control the work lights? 

66. Define polarity-type distribution panel. Make a sketch of a three-wire polarity 
panel. Make a sketch of a two-wire polarity panel. What is the advantage of a polarity 
panel over that of an ordinary panel? 

67* Draw a sketch to illustrate two methods, which are used in the Major system, 
of connecting the magazine circuits to the remote-board busbars. Why is it sometimes 
desirable to connect a two-pole magazine switch as a three-pole switch with a solid 
neutral? 

68. Show by sketch how the Major pilot board is fed. 

69. Explain how the Major system may be electrically "locked.” Draw a sketch to 
illustrate. 

70. Show by diagram how a lamp may be connected to indicate whether the pilot 
board is “dead” or “alive.” 

71. Show by sketch how the indicating lamps on the individual pilot switches are 
connected. 

72. What pilot switches are not provided with indicating lamps? Why? 

73. Make a sketch to show how all of the stage and house lights may, in theMajor 
system, be controlled by a two-circuit momentary contact switch. Explain the utility 
of this feature. 

74. What are theatre dimmers? Into what part of the circuit are they connected? 
Explain how dimmers are operated. 

75. Give the Code requirement relating to the method in which dimmers must be 
wired. Draw sketches to illustrate two methods of complying with this requirement. 

76. What is the maximum wattage rating of a single dimmer plate? How is a 
lamp-load greater than this maximum wattage dimmed? Make a sketch to show the 
correct method of connecting two or more dimmer plates to dim one lamp-group. 
Make a sketch of an incorrect method. Explain how this incorrect method may result 
in burning out all of the dimmers in the unit. 

77. What is the general rule to be followed in fusing the stage-switchboard circuits? 

78. Make a diagram to illustrate a method which is sometimes employed in wiring 
the footlights. Explain the utility of this method. 

79. Draw a feeder diagram for the electric wiring of a theatre. Show the location 
of the service entrances, and the location of all cabinets, panel boxes and switchboards. 



INDEX 


Page 


Page 


A 


Adam, F., Electric Co., sec Frank 
Adam. 

Aisle light. 358 

Alarm-clock switch. 330 

Alternating-currentseries circuits 317 
“American Electrician’s Hand¬ 
book,” Croft, T., on 

Kelvin’s law. 302 

A. I. E. E. Standardization 

Rules, on temperature rise. 24 
Anderson time switch, classi¬ 
fication. 338 

description. 331 

Anderson mfg. co., individual 

series lamp control. 344 

time switch devices. 336 

time switch wiring. 342 

Apartment houses, hallway lights 

control. 340 

Arc lamp control. 311 

lights. 364 

Arco Wand cleaner. 184 

Arrow' electric co., binding 

post. 34 

snap switch. 40 

Auditorium lights. 309 

Auto-transformer. 343 

Automatic Switch Co., clapper 

switch. 282 

relay.’. 296 


B 


Barrier application. 

definition. 

Base, knife switch area, 

decrease. 

material. 

Baseboard outlet. 

Bases, link-fuse cutouts. 

material. 

support. 

Beaver machine & tool co., 

straight-through switch- 

tandem switch... 

Binding posts, definition. 

use. 

see also Terminals. 
Blade-and-jaw contact. 


92 

21 


92 

28 

106 

110 

37 

87 

14 

52 

33 

27 

31 

461 


Blades, knife switch. j . 24 

Blocks, flush switch box 

support. 104 

Border lights, application.... 364 

wiring. 410 

Branch circuit, definition... 3 

emergency cabinet.. 357 

feeding.*. . . 229 

fusing. 120 

single-pole switch. 101 

Break- and hinge-jaws. 91 

Brookins Co., aisle-lamp. 358 

Bryant electric co., branch 

circuit mastering. 239 

canopy switch. 64 

door switch. 53,321 

duplex switch. 254 

electrolier switch. 253 

flush switch. 66 

four-way switch. 77 

heater switch diagram. 264 

circuit connection. 266 

indication. 261 

lever-type switch. 49 

MASTER SWITCH CIRCUIT, 

three-wire. 235 

two-wire. 210 

plug in neutral-wire cutout.. 120 
pull switch, illustration .... 57 

use. 60 

snap switches, pendent. 63 

rotating-button. 42 

surface switch. 68 

Bull switch. 367 

Burglar circuit. 203 

Busbars. 404 


C 


Cabinet, definition. 

. 22 

Front doorman’s. 

. 466 

Indiana theatre. 


Canopy switch. 

. 64 

Carter system, garage 

light- 

ing. 

. 182 

universal mastering. . . . 

. 229 

wiring diagram. 

. 191 

Cartridge enclosed fuse... 

. 115 

Ceiling lamps, control.. 

. 310 

emergency circuit. 

. 359 







































































462 


INDEX 


Page 


Ceiling-type pull switch, 

definition.13 

operation. 57 

use. 60 

Circuit, broken. 1 

connections, electrolier 

switch. 245 

four-way switch. 159 

heater switch. 263 

incorrect, three-way switch 158 

snap switches, classifica¬ 
tion . 66 

series-parallel. 78 

three-pole. 73 

three-way. 75 

switch classification. 15 

time switch. 339 

control, double-pole switch 138 

stage switchboard. 369 

transformer. 342 

see also Control. 

definition. 1 

diagrams door-bolt switches 327 

electrolier switch. 246 

Major system. 392 

remote- and direct-control. 314 
emergency, see Master circuit. 

external. 1 

feeder, see Feeder. 

internal, definition. 1 

duplex switch. 254 

layout, theatre. 355 

master see Master circuit. 

nomenclature. 1 

open. 1 

remote-controlled switch. 271 

restricted. 131 

short. 1 

small-residence. front. 

two branch. 210 

Clapper switch. 276 

Code requirements, outline.. . 85 

remote-controlled switch. 299 

time switches. 344 

Code violation, Carter system 194 

Color-main switch. 367 

Combination switch. 18 

Commutating switch, defini¬ 
tion. 18 

four-way. 76 

Conductivity, copper. 25 

Conductor, Carter connection. 198 
identification, master cir¬ 
cuit.*. 241 

polarity wiring. 124 

three-way switch. 185 

snap switch. 33 

Conduit, size. 123 


Page 

Connecticut Electric Mfg. Co., 


snap switch. 39 

Connecting-lugs. 27 

Constant-circuit switch, 

definition. 368 

use. 401 

Constant-circuit work lights.... 401 
Constant-current transformer. . 342 

Contact, auxiliary. 94 

blade-and-jaw. 31 

block. 91 

button. 16 

terminals, link fuses. Ill 

Contactor, double-deck switch 71 

insulation. 37 

magnetic.*. 285 

mechanisms. 35 

stationary. 33 

Control, arc lamps. 311 

ceiling lamps. 310 

CIRCUIT, REMOTE-CONTROLLED 

switch, definition. 287 

protection. 299 

circuit, see also Circuit control. 

dimming. 140 

electrolier.. . 142 

four-location, diagram. 147 

switches. 168 

heating appliance. 108 

master circuit. 312 

multi-location, Carter sys¬ 
tem. 192 

double-pole switches. 148 

economy. 309 

four-way switches. 166 

lamps. 258 

remote-controlled switches. 288 

panel. 356 

pilot switch. 393 

pre-selective. 387 

REMOTE-CONTROLLED SWIT¬ 
CHES, methods. 298 

momentary-contact. 288 

restricted. 6 

restricted-selective, defi¬ 
nition . 7 

double-pole switches. 139 

stair-way lighting. 177 

selective. 6 

series-parallel. 140 

three-location, Carter sys¬ 
tem. 200 

diagram. 147 

hall lamps. 177 

switches. 166 

time switches. 339 

two-location, Carter system 196 
diagram. 146 

























































































INDEX 


463 


Page 

Control, two-location, Cont'd. 


switches. 163 

Copper, conductivity. 25 

wires, fusing... 118 

Cord switch. 15 

Converter, control panel. 356 

Cross-bar, definition. 29 

securing to blade. 91 

Cradle spots. 443 

Croft, T., on heater switches.. 262 

Kelvin’s law. 302 

Cutler-Hammer Mfg. Co., 

door switch. 322 

door-bolt switch. 328 

momentary contact switch. .. 288 
reciprocating blade switch.... 12 

remote-controlled switch. 277 

straight-through switch. 63 

tandem switch. 49 

Cutout, automatic. 116 

definition. 21 

link-fuse. 110 


D 


Dayton Lighting Co., on street 

lamp control. 318 

“Dead front” switchboard. 371 

Dimmer bank. 406 

circuit, as heater circuit. 260 

series-parallel. 151 

location. 381 

Major system. 390 

use. 406 

Dimming control. 140 

lights. 131 

Direct- and remote-control sys¬ 
tem, combined. 314 

Direct-control system, cost.. 301 

wire saving. 307 

Distribution box. 22 

center, construction. 22. 

definition. 4 

panel, fuse arrangement. 119 

polarity-type. 402 

remote-controlled switch... 309 

Door switch circuits. 270 

description. 321 

one-button. 53 

Double-deck switches, 

definition. 69 

electrolier. 252 

Double fuse connection. 149 


Double-pole switch, branch 

circuits. 

connections. 

construction. 

definition. 


Page 

Double-pole switch, Continued. 


heater..*. 266 

knife. 171 

magazine. 386 

master circuit. 234 

two-branch circuit. 225 

relay. 296 

remote-controlled. 279 

Double-throw operation, 

remote-controlled switches. 294 

switch, definition. 19 

mounting. 99 

Dressing-room cabinet. 363 

Drilling dimensions, remote-con¬ 
trolled switch. 278 

E 

Eberson, J., on Indiana Theatre 

wiring specifications. 411 

Edison system, street lamps.. 318 
Electric circuit see Circuit. 

Electrical Mfg. Co., stage 

switchboard’. 382 


“Electrical Review” on three- 

way switch installation.... 182 
“Electrical South” on lamp 
control in moving picture 


studios. 311 

Electrolier control see Control, 
restricted-selective. 

switch, connections, etc. 244 

definition. 19 

single-pole, Code. 244 

types. 78 

Electromagnet, shell-type. 316 

Emergency cabinet, definition 357 

Indiana Theatre. 448 

Emergency circuit see Master 
circuit. 

lamp, lighting energy. 350 

requirements. 358 

lighting, separate circuits. . . . 203 

service board. 356 

connections. 350 

Energy, genera 1-lighting 

service. 353 

general-power service. 350 

Exciter. 298 

Exit sign lamps. 358 

Extension lamp wiring. 152 

F 

Fan-motor switch. 251 

Feed wires. 187 

Feed-through switch. 15 

Feeder, definition. 2 

diagram, Indiana Theatre.... 453 
stage switchboard. 367 
















































































464 


INDEX 


Page 


Fire-engine house, lighting. 205 

Fixture wire, fusing. 118 

Flat-rate sign control. 316 

Float-switch. 298 

Floor-outlet box. 103 

Flush switch, application. 60 

bases. 37 

box. 103 

definition. 14 

four-way. 78 

installation. 105 

push-button. 13 

wiring diagrams. 65 

see also Snap switch. 

Footlights, stage lights. 364 

wiring. 410 

Four-point switch, defini¬ 
tion. 16 

illustration. 11 

Four-pole switch. 17 

Four-position, double-deck 

switch. 252 

Four-way switch circuit 

connections. 159 

description. 155 

Four-way switch, definition .. 18 

flush. 78 

revolving-blade. 76 

three-location control. 170 

two-location control. 163 

Frank Adam Electric Co., 


floor outlet box. 104 

front doorman’s cabinet.446 

general-power cabinet. 430 

magazine cabinet. 434 

Major pilot board. 432 

switch. 391 

Major system. 397 

on Major board equipment. . 406 
remote-control stage 

switchboard. 387 

remote board. 440 

remote-controlled switch. 279 

service cabinets. 428 

stage lights. 365 

pocket. 352 

Front-doorman’s cab i n e t, 

function. 362 

Indiana Theatre. 446 

Fuses, branch circuits. 122 

classification. 108 

emergency-lamp. 359 

enclosed. Ill 

remote-controlled switch. 299 

terminals. 91 

Fusing. 409 


Page 

G 


Garage circuit control. 182 

General Electric Co. elec¬ 
trolier switch, installa¬ 
tion. 59 

illustration. 246 

wiring. 249 

fan motor. 252 

General-lighting 

cabinet, description. 360 

Indiana Theatre. 428 

service. 350 

General-power 

cabinet, description. 356 

Indiana Theatre. 430 

service. 350 

Generator. 298 

Grand-master lever. 377 

Gridiron. 365 


H 


Hall lights, restricted-control 

system. 173 

time switch control. 340 

wiring. 159 

Handles, knife switch. 29 

Hart Mfg. Co., binding post. . 34 

contactor insulation. 37 

distribution panel. 309 

door switch. 323 

double-throw switch. 297 

emergency lighting. 204 

indicating dial. 80 

relay. 295 

remote control circuit. 289 

REMOTE-CONTROLLED SWITCH 

control. 299 

master. 313 

three-pole. 273 

two-pole. 286 

switch cover. 38 

wiring. 65 

Hart & Hegeman Mfg. Co., 

momentary-contact switch. 55 

Heater switch, circuits. 244 

definition. 259 

kinds used. 260 

see also Series-parallel switch. 

Heating appliance. 108 

Hill-and-valley movement. 49 

Hinges, knife switch blade. 25 

Hospital, remote-control system 291 
Hotel-room door-bolt switch.... 328 

House bull switch. 367 

lights control. 405 


























































































INDEX 


465 


Page 

House lights Continued. 

definition. 364 

main. 393 

switch. 367 

master switch, definition.... 367 

function. 393 

pilot switch. 401 

Hutchings, O. H. on street lamp 

control. 318 

I 

Identification, conductors, see 
Conductors. 

Incandescent lamps circuits, 


remote-control. 317 

pocket lights. 364 

Indiana Theatre, control 

cabinets. 455 

cradle spots. 443 

emergency cabinet. 448 

feeder diagram. 453 

front doorman’s cabinet. 446 

general-lighting cabinet. 428 

general-power cabinet. 430 

magazine cabinet. 434 , 

Major pilot board. 432 

remote board. 441 

panel, picture booth. 450 

pilot board... 451 

remote board. 440 

sign cabinet. 449 

stage switchboard schedule. .. 435 

wiring plans. 414 

specifications. 410 

Indicating lamps, Major pilot 

switch. 405 

three-way switch. 166 

Insurance requirements, see 
Code. 


J 

r 

Jaws, knife switch. 25 

Jones, J. B., on single-pole 

switches. 102 

Jones, W. S. on emergency 

lighting. 203 

K 

Kansas City Electric Light Co. 

on street lamp lighting. 152 

King, D. E., on remote control. 321 

Knife blade switch. 10 

Knife-handle switch. 13 

Knife switch, auxiliary con¬ 
tacts. 94 


Page 


Knife switch, Continued. 

base. 28 

blades, connections. 29 

current-carrying capacity.. 24 

classification, form. 30 

voltage. 86 

connecting lugs. 27 

connection. 135 

construction. 23 

cost. 32 

handles. 29 

jaws, construction. 25 

turning, prevention. 91 

marking. 86 

nomenclature. 23 

spacings, barriers. 93 

minimum. 87 

troubles. 31 

two-location control. 133 

universal master circuits. 227 

use. 127 

wiring, Code rule. 99 

method. 27 


L 

Lamont, L. H. & Co., three-way 


switch. 181 

Lamp-feed wire. 185 

Lamp lighting, three-wire 

system. 152 

Lamps, ceiling fixture. 310 

CONTROL, MASTER CIRCUIT, 

single-location. 207 

two-location. 212 

control, moving picture 

studios. 311 

MULTI-LOCATION . 258 

remote-control system. .. 309 

several branches. 308 

three-location. 147 

two-location, double- 

pole knife switch. 146 

pull switch. 62 

single-pole knife switch.. 133 
series-parallel connections.... 145 
see also Arc lamps. 

Lead. 5 

Leg.. 5 

Lever-blade switch. 11 

Lever, grand-master. 377 

pre-set master. 379 

switch construction. 23 

snap. 48 

Lighting circuit see Circuit. 

direct-control, cost. 301 

main see Main. 

remote-control, cost. 301 













































































466 


INDEX 


Page 

Lights, diming. 131 

stage switchboard control.... 364 

Link fuses. 109 

Live front switchboard. 371 


Load balancing, switch connec¬ 
tion, 132 

three-wire-neutral system... . 148 
Lobby basement, service boards 354 


cabinet. 362 

Location control, definition. 203 

Lock-bolt, door, switch opera¬ 
tion .. 330 

Lugs, connecting. 27 


M 


Magazine cabinet. 434 

circuit, connecting energy 

source. 403 

definition. 368 

panel connection. 402 

definition. 368 

location. 381 

sub-feeder. 368 

switch, definition. 368 

lever mechanism. 384 

Magnet switch. 270, 285 

Magnetic contactor. 285 

Main, definition. 3 

switch, emergency-cabinet... 357 
three-phase, load balancing.. 132 
Major, R. E., on Indiana Thea¬ 
tre wiring specifications... . 411 
remote-control stage switch¬ 
board. 387 

Major system, advantages... . 387 

circuit diagram. 395 

constant-circuit work lights. . 401 

dimmers. 390 

fusing. 409 

locking. 404 

magazine circuit connections 403 

pilot board feeding. 404 

illustration. 388 

Indiana Theatre. 432 

pilot switch classification... 400 

indicating lamps. 405 

unit. 390 

pre-selection control. 387 

remote board, illustration... 389 

Indiana Theatre. 441 

switches. 398 

single lamp-group, circuit 

diagram. 392 

switch connection. 403 

illustration. 279 

Manual switchboard. 371 


Page 


Master circuit control, switch 312 

electrolier switch on. 258 

feeding. 235 

lamps, multi-location-c o n- 

trolled. 216 

one- and two-location-con¬ 
trolled. 215 

part connected. 221 

single-location-controlled.. . 207 
two-location-controlled. . . . 212 

old building, installation. 211 

stairway. 211 

straight, two location control 230 

switches. 240 

testing. 241 

three-wire system arrange¬ 
ment. 237 

connections. 232 

two branches. 220 

universal. 222 

use. 205 

wiring, Code requirements .. 207 

diagram, residence. 215 

Master lever. 377 

switch, definition. 20 

double-pole. 234 

location. 205 

pilot. 368 

remote-controlled. 312 

three-wire system. 232 

types. 207 

universal master circuit.... 225 

wiring. 228 

“ Mercury ” time switch. 334 

Meter cutouts. 112 

circuit around. 161 

service, two-rate, control.341 

Metropolitan Electric Mfg. 

Co., switch. 385 

switchboard. 381 

Mogul receptacles. 122 

sockets. 122 

Momentary-contact switch, 

definition. 20 

operation. 54 

stage light control. 405 

two-circuit. 293 

Motor, theatre. 350 

Motor-generator control panel.. 356 

Movable contactors. 33 

Moving-picture theatre light 

control. 309 

Multi-deck switches, defini¬ 
tion. 70 

electrolier. 247 

Multi-location control, elec¬ 
trolier switch. 258 

master circuit. 216 

















































































INDEX 


467 


Page 

Multi-pole switch, applica¬ 


tions. 134 

circuit. 127 

knife blades. 29 

remote-controlled, master.... 314 
Mutual Electric & Machine 

Co., dimmer bank. 407 

magazine switch. 386 

switch levers. 383 

switchboard, stage. 370 


N 

National Electrical Code, see 


Code. 

Night-and-day lamp. 141 

N-pole switch. 17 

No-voltage release. 298 

O 

“Off circuit”. 158 

Oil switch. 321 

One-button switch, door. 53 

snap. 43 


One-point switch see Single-point 
switch. 

One-pole switch see Single-pole 


switch. 

Oscillating blade switch. 10 

Outdoor signs, control. 339 

Overload release. 298 

P 

Panel board. 22 

box. 228 

Indiana Theatre. 454 

picture booth cabinet. 450 

“Paragon” time switch. 334 

Parallel switch.. . 262 

Pendent switch application... 62 

definition. 14 

Phase wire. 5 

Picture-booth cabinet, de¬ 
scription. 362 

panel. 450 

Pierce Electric Co., feeder 

diagram. 453 

on wiring specifications. 411 

wiring plans. 415 

Pilot board, definition. 368 

Indiana theatre. 451 

Major system. 388 

Pilot lamp, double-pole switch 141 

three-way switch. 166 

Pilot switch, individual. 368 

wiring diagram. 392 


Page 


Plug connectors. 108 

cutout, master circuit. 226 

neutral-wire. 120 

stage pocket. 353 

Pocket lights, incandescent. 364 

Polarity identification, marked 

wire. 124 

opposite, spacings. 90 

Polarity-type distribution panel 402 
Poultry houses, time switch 

control. 341 

“Power Plant Engineering,” 
Jones, W. S., on emergency 

lighting. 203 

Pre-selective control. 387 

switchboard operation. 383 

Pre-set master levers. 379 

stage switchboard. 381 

Pressure regulator. 298 

Primary circuit, remote control 321 
Pringle Electrical Mfg. Co., 

quick-break switch. 386 

stage switchboard. 375 

Proscenium lights, descrip¬ 
tion. 364 

wiring. 410 

Pull switch, canopy. 65 

definition. 13 

surface. 57 

Push-button switch, classifi¬ 
cation . 43 

definition. 13 

pendent. 63 

Q 

Quick-break switch, knife.... 94 

stage switchboard. 386 

R 

Race way-work sub-bases. 108 

Railway stations, time switch. . 341 

Receptacles, installation. 103 

Reciprocating-blade switch. 12 

Relay. 294 

Release, no-voltage... . 298 

overload. 298 

Release-catch switch. 45 

Remote-and direct-control sys¬ 
tem, combined. 314 

Remote board, definition. 367 

Indiana Theatre. 440 

Major system. 389 

Remote-control, circuits. 321 

distribution panel. 309 

series circuit. 317 

several branch circuits. 308 














































































468 


INDEX 


Page 


Remote-control, Continued. 

stage switchboard. 387 

street lamps. 318 

switch. 270 

switchboard, definition. 366 

description. 371 

system, cost. 301 

hospital... 291 

wire saving. 307 

Remote-controlled switch 

clapper type. 276 

control circuits, definition 287 

protection. 299 

currents. 276 

definition. 270 

drilling dimensions. 278 

master. 312 

moving picture studios. 311 

oil. 321 

operation. 292 

prices. 315 

sign control. 316 

single-pole. 398 

three-pole illustration. 283 

operation. 272 

two-pole. 281 

Residence, circuits and 
switches front. 

wiring diagram, master cir¬ 
cuit. 221 

Return wire. 185 

Revolving-blade switch, defi¬ 
nition. 10 

four-way. 76 

operation. 39 

three-way. 73 

Rich, C. A., on switch installa¬ 
tion. 321 

Rigging loft. 365 

Rosettes, fused. 122 

Rotary-button switch, Can¬ 
opy . 64 

definition. 13 

surface. 39 


S 


“Saturday night overtime” 

device. 336 

Screws, supporting bases. 87 

Season changing device, time 

switch. ?jU . 337 

Secondary circuit, remote-con¬ 
trol. 321 

Series lamp circuit, remote 

control. 317 

time switch control. 341 

Series-parallel control. 140 


Page 


Series-parallel Continued. 

switch, connections. 78 

definition. 263 

see also Heater switch. 

Series switch, definition. 262 

Service boards location. 354 

connection, definition. 4 

fuse, enclosure. 116 

theatre. 353 

switch, application. 94 

definition. 20 

three-wire-system. 148 

wires, theatre. 348 

Shop cabinet. 363 

Short circuit. 1 

Show-window lights, re¬ 
stricted-control. 173 

time switch, control. 340 

Side, circuit. 5 

Sign cabinet, Indiana theatre 449 

use. 361 

Signalling installation. 17 

Signs, remote-controlled. 316 

time switch control. 339 

Single - location - controlled 

lamps, master circuit. 207 

universal mastering. 223 

Single-point switch, definition 16 

illustration. 11 

Single-pole switch. 

circuits. 127 

combined, use. 251 

with electrolier switch. 254 

connections. 128 

control, double-pole switch 137 

three-location. 147 

individual lamp-groups, cir¬ 
cuit . 239 

two-location. 165 

damp places. 100 

definition. 17 

door-bolt. 329 

heater. 263 

in mastered circuit. 240 

master. 216 

operating remote-controlled 

switch. 292 

remote-controlled. 398 

service switch. 100 

snap. 67 

Single-throw switch, defini¬ 
tion. ...**♦.» .. 18 

installation. 99 

Sliding door, switch installation 329 

Smith, F. H., on feeders. 317 

Snap switch, application. 60 

base. 37 

Code recommendation. 107 


























































































INDEX 


469 


Page 

Snap switch, Continued. 

binding-posts. 265 

button. 38 

circuit connection. 66 

conducting parts. 33 

constant-circuit. 401 

covers. 38 

definition. 15 

double-pole, connection. . . . 135 

construction. 71 

electrolier. 78 

forms. 58 

four-way. 76 

handle. 38 

heater. 260 

indicating. 80 

insulating material. 37 

lever-type. 48 

mechanism, description. 32 

operation. 38 

momentary-contact. 54 

multi-deck. 247 

non-indicating. 80 

one-button. 43 

pendent. 62 

push-button.. 43 

release-catch type. 45 

revolving-blade. 39 

rotating-button. 39 

series-parallel. 78 

single-pole. 67 

straight-through. 63 

sub-base support. 107 

tandem two-button. 48 

terminals... 265 

tests. 81 

three-pole. 73 

three-way. 73 

two-button.. 45 

wiring. 65 

see also Surface switch, Flush 
switch. 

Sockets, keyless. 207 

Solenoid door-bolt switch. 323 

Specification, wiring. 410 

Spot lights. 365 

Sprague Electric Works, inter¬ 
locking switchboard. 378 

Stage basement service boards 354 

bull switch. 367 

lights, control. 405 

definition. 364 

distribution na ^l,. . . 309 

pilot switch. 401 

pocket. 352 


switchboard circuit control.. 369 

circuits, fusing. 409 

classification. 372 


Page 

Stage switchboard, Continued. 


description. 364 

dimmers. 381 

feeders. 367 

interlocking. 375 

lights. 364 

magazine panel. 381 

switches. 385 

nomenclature. 367 

non-interlocking. 372 

pre-selective. 383 

pre-set. 381 

remote-control, defini¬ 
tion. 371 

principal type. 387 

schedule, Indiana Theatre. 435 

Stage-main switch. 367 

Stage-master switch. 367 

Stairway lighting, Carter 

system. 197 

master circuit. 211 

restricted-selective. 177 

Stationary contactors. 33 

“Standard For Snap 
Switches,’’Underwriters’ 
Laboratories, on tempera¬ 
ture rise. 24 

test specifications. 81 

Standard system, master 

circuit. 230 

switch circuit wiring. 192 

Stop, switch. 27 

Storage-battery circuit. 351 

switch control. 298 

Storerooms, three-way switch 

circuits. 181 

Straight master circuit. 206 

Straight mastering, single¬ 
location-control. 207 

three-location-control. 216 

two-location control. 231 

Straight-through switch, 

definition. 14 

illustration. 63 

Street lamps, remote control 318 

time switch control. 341 

Sub-base, definition. 21 

supporting switches. 107 

Sub-feeder. 3 

Sub-main. 3 

Sub-master pilot switch, 

circuit diagram. 393 

definition..... 368 

Sunday shut- oi? device. 336 

Sundh Electric Co., remote- 
controlled switch, illus¬ 
tration .. 283 

price and ratings. 315 
































































































470 


INDEX 


Page 

Surface switch, application 60 

bases. 37 

definition. 14 

illustration. 10 

indicating. 97 

three-pole. 73 

three-way. 73 

wiring. 68 

see also Snap switch. 

Switch base. 87 

blades, locking. 26 

mechanism. 10 

circuit connections. 15 

multi-pole. 127 

restricted-control. 173 

single-pole. 127 

classification. 7 

combinations, Carter system 194 

commutating. 76 

connection, Carter system 229 

Major system. 403 

construction. 23 

definition. 7 

feed wire. 185 

four-location control. 147 

four-point, definition. 16 

illustration. 11 

fusing. 91 

installation. 98 

magnetic.. 285 

Major pilot. 400 

momentary-contact. 288 

mounting design. 14 

nomenclature. 1 

one-point see Switch , single¬ 
point. 

operating method. 12 

position. 15 

remote-controlled, see Remote. 

service. 94 

single-point, definition. 16 

illustration. 11 

small-residence. front. 

special. 241 

stop. 27 

symbols. 7 

temperature rise. 24 

terminal. 27 

three-location control. 147 

three-point, definition. 16 

illustration.. 11 

three-position electrolier. 245 

travelers. 185 

two-location control. 146 

two-point, definition. 16 

illustration. 11 

types. 385 


Page 

Switch, Continued. 

see also entries under Knife , 
Snap, Single-pole etc. 
Switchboard, remote-control.. 366 
see also Stage switchboard. 
Switch-lock-out device. 337 

T 

Tandem switch. 48 

Tank switch. 298 

Tap circuit, definition. 3 

fusing. 120 

Temperature rise, switch. 24 

Terminal plates, see Binding 
posts. 

Terminals, enclosed fuse. 113 

loose. 31 

snap switch marking.. 265 

Theatre circuit layout. 355 

dimmers. 406 

lighting. 348 

Thermostatic regulator.. .. 298 

Three- and four-way switch 

connections. 229 

Three-circuit electrolier 

switch, using fan switch 251 

wiring. 256 

Three-deck switch. . ... 70 

Three-location control circuit, 

conductor. 190 

Three-location-controlled lamp- 

group, straight mastering.. 216 
Three-phase mains, load balanc¬ 
ing. 132 

Three-point switch, definition 16 
fan-motor, used as electrolier 251 

illustration. 11 

Three-pole switch, definition 17 

double-throw. 149 

remote-controlled, clapper 276 

straight-line. 272 

snap. 73 

Three-position, two-point switch 245 
Three-way and four-way 

switch, two-location control 165 
switch as single-pole, Code 

rule. 103 

utilization. 155 

switch circuit, by-passing 

meter. 161 

conductors. 185 

connections. 75 

control, garage. 182 

restricted. 174 

discussion. 155 

indicating lamps. 166 

stairway lamps. 180 



















































































INDEX 


471 


Page 

Three-way switch circuit, Cont’d. 


testing. 186 

wiring. 158 

switch, definition. 18 

flush. 74 

revolving-blade. 73 

surface. 73 

wiring. 161 

Three-wire, four-branch in¬ 
stallation, master circuit... 234 

system, d.c. 5 

lamp lighting. 152 

master circuit, arrange¬ 
ment. 237 

diagrams. 232 

service switch. 148 

single-pole switch. 101 

Throw-over switch, automatic 297 

manual. 149 

Time switch circuits. 270 

Code requirements. 344 

controlling remote-controlled 

switch. 298 

definition. 330 

Toggle switch, definition. 13 

operation. 58 

Topeka Edison Co., on flat-rate 

sign control. 316 

Transfer switch. 149 

Transformer, circuit control.... 342 

Traveler, definition. 5 

Trumbull Electric Mfg. Co., 
service entrance devices.... 96 

single-pole switch. 69 

stage switchboard. 372 

Tumbler switch, see Toggle 
switch. 

Two-button snap switch. 45 

Two-circuit, four-position elec¬ 
trolier switch. 248 

momentary contact switch. .. 298 
Two-location control, long 

cord. 62 

of master circuit. 231 

on master circuit. 212 

single-pole switches. 133 

Two-point switch, definition.. 16 

illustration. 11 

Two-pole switch, see Double-pole . 

Two-position, definition. 39 

Two-rate meter service control 341 


U 

Underwriters’ Laboratories, 


on temperature rise. 24 

test specifications. 81 

Underwriters’ requirements.... 85 


Page 


Universal master circuit, 

definition. 206 

diagram. 223 

V 

Vacuum cleaner motor. 183 

Voltage, theatre. 353 

W 

Wall lamps. 359 

Wall-type switch. 60 

Warehouses three-way switch 

installation. 181 

Warming coil, time switch. 337 

Wattage, dimmer plate. 408 

Wire connection, knife switches 27 

permanently grounded. 118 

polarity identification mark¬ 
ings. 124 

saving, Carter system. 193 

direct-control system. 307 

double-pole switch. 138 

remote-control system. .289, 307 

ungrounded service. 98 

Wire-size, change, fusing. 117 

Wiring aisle-light fixture. 359 

border lights. 410 

Code violation. 194 

diagram, Carter system. 191 

electrolier switch. 249 

flush switch. 65 

master-circuit, residence 215 

three-wire systems. 232 

universal-control. 223 

pilot switch. 392 

remote-controlled master 

switch. 314 

snap switch. 65 

surface switch. 68 

symbols. 8 

extension lamp. 152 

footlights. 410 

lay-out, three-way switch 

circuit. 159 

master-circuit, Code re¬ 
quirements. 207 

completed building. 228 

plans, Indiana theatre. 414 

proscenium lights. 410 

remote-control system. 291 

vacuum cleaner motor. 183 

specifications, Indiana thea¬ 
tre. 410 

three- and four-way switch 

circuits. 192 

three-way switch circuits. 158 














































































472 


INDEX 


Page 


“Wiring for Light and Power,” 

T. Croft, on heater switches 262 
Worcester Electric Light Co., on 

lamp circuits. 317 

Work lights, constant-circuit 401 
definition. 365 


Page 

Wynkoop, H. S , on stage 


switchboards. 371 

Y 

Yard wires. 94 


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